The now time was very close to my edits as I had been listening as I tweaked.
 
I might add I had 3 take lanes open, and was comping the track,  there were a few spots where all three takes had late hits ( I know, practice more)  so I split a take, slip edited the clips head and tail a bit with fades too, then nudged the time to line it up.  Then I hit the space bar which took me to zero....

brundlefly

Jlien X
This is an annoying issue. It happens when I use Ctrl+Shift+PageUp/Down (all on the right side of the keyboard) to move between markers (and I have no marker at the beginning of the song).

Possibly you're inadvertently hitting Ctrl+Home on occasion?.
 
This won't help avoid that, but just incidentally, I found that I never used Page Up/Down to page tracks, so I re-mapped Page Up/Down to previous/next measure, and Ctrl+Page Up/Down to previous/next marker. Saves some keystrokes. I try to avoid combos where I have to hit more than one modifier for the most common tasks.

 
It's unlikely to hit the Home key when your thumb and forefinger are on Ctrl and Shift keys and the third finger on PageUp/Down (it's likely to hit the Insert key but it creates a new track and it never happend to me). Also, although I didn't mention it, a month or two ago I came up with a better key mapping for the left hand area (because after all these years I found it tiring to use my right hand, which I want to keep on the mouse as much as possible, to the keyboard just to move between bars or markers. My new shortcut key mapping is this:
 
W = Go to start of this measure
E = Go to end of this measure
Shift+W = Previous Marker
Shift+E = Next Marker
Ctrl+Space = RTZ
 
(Place your thumb on Spacebar, little finger on Shift, middle finger on W, and forefinger on E. If you have the "On Stop, Rewind to Now Marker" enabled, hit Ctrl+Space, with the little finger and thumb, once to pause (or stop without automatically rewinding to the Now time marker), and hit the keys again if you want to go back to the beginning of the song)
 
 
Because this new mapping is SO good, I thought maybe I should recommend it to others. BUT, I've been experiencing a strange behavior. When I use Shift W/E to move between markers, sometimes the Now time marker jumps to Bar 1 and automatically starts playback (although playback wasn't running before I hit Shift W/E). So the Now time marker jumping to Bar 1 seems to be a bug (You've never experienced it? Try moving between markers using shortcut keys more often, and do it faster. I didn't experience the issue in X2/X1 btw). And, as for the playback automatically starting from Bar 1, I remembered the default Shift+W behavior. Although both "W" and "Shift+W" are described as "RTZ" in Edit>Preferences>Customization>Keyboard Shortcuts, "Shift+W" not only does RTZ but also starts playback from there. Maybe this itself is a bug? I'll probably report it to CW.

It happens to me whenever I have been pressing the spacebar a lot to stop and start playback.  When it happens, pressing the spacebar twice will bring it back to the original position.
 

Kev999
It happens to me whenever I have been pressing the spacebar a lot to stop and start playback.  When it happens, pressing the spacebar twice will bring it back to the original position.
 

I've also noticed this fairly regularly. I don't know if it's related to holding the spacebar down longer than normal or what. It almost seems like there's something in there by design to allow you to go back to either the now marker or the beginning, but I don't know what it is.

Jlien X
When I use Shift W/E to move between markers, sometimes the Now time marker jumps to Bar 1 and automatically starts playback (although playback wasn't running before I hit Shift W/E). So the Now time marker jumping to Bar 1 seems to be a bug (You've never experienced it? Try moving between markers using shortcut keys more often, and do it faster. I didn't experience the issue in X2/X1 btw). And, as for the playback automatically starting from Bar 1, I remembered the default Shift+W behavior. Although both "W" and "Shift+W" are described as "RTZ" in Edit>Preferences>Customization>Keyboard Shortcuts, "Shift+W" not only does RTZ but also starts playback from there. Maybe this itself is a bug? I'll probably report it to CW.

So I'm a little confused because your first post said you were using the default accelerators for previous/next marker, but with this new scenario two possibilities seem likely: Either the keybinding functionality itself is flaky and Shift+W is intermittently reverting to it's default behavior of RTZ-and-start-playback or you're sometimes failing to get Shift pressed in advance of W and hitting W alone is giving you RTZ without starting playback as it should.
 
In any case, it would seem that one way or another using Shift+W as your previous marker command is likely causing unexpected RTZ in your case.
 
All I know is I've never encountered this issue, and can't reproduce it now by any of the actions suggested in this thread. Some part of the puzzle is still missing for the other cases.
 
 

brundlefly

Jlien X
When I use Shift W/E to move between markers, sometimes the Now time marker jumps to Bar 1 and automatically starts playback (although playback wasn't running before I hit Shift W/E). So the Now time marker jumping to Bar 1 seems to be a bug (You've never experienced it? Try moving between markers using shortcut keys more often, and do it faster. I didn't experience the issue in X2/X1 btw). And, as for the playback automatically starting from Bar 1, I remembered the default Shift+W behavior. Although both "W" and "Shift+W" are described as "RTZ" in Edit>Preferences>Customization>Keyboard Shortcuts, "Shift+W" not only does RTZ but also starts playback from there. Maybe this itself is a bug? I'll probably report it to CW.

So I'm a little confused because your first post said you were using the default accelerators for previous/next marker, but with this new scenario two possibilities seem likely: Either the keybinding functionality itself is flaky and Shift+W is intermittently reverting to it's default behavior of RTZ-and-start-playback or you're sometimes failing to get Shift pressed in advance of W and hitting W alone is giving you RTZ without starting playback as it should.
 
In any case, it would seem that one way or another using Shift+W as your previous marker command is likely causing unexpected RTZ in your case.
 
All I know is I've never encountered this issue, and can't reproduce it now by any of the actions suggested in this thread. Some part of the puzzle is still missing for the other cases.
 

 
Although I now mainly use Shift+W/E to move between markers, I sometimes still use the default Ctrl+Shift+PageUp/Down when my right-hand is available. Either way I encounter this RTZ issue from time to time, but the RTZ-and-start-playback issue only occurs when I use Shift+W/E. But the second possibility you cited isn't possible because, as I said in my second post, I assigned "Go to start of this measure" to the W key. So I think it's the first possibility that's causing the issue. 

Just an update..., working on the same project as I'm practicing my solo prior to recording.  Using the space bar to start play, no editing, no fat fingers, space bar only, there were several times it went back to zero. pressing space bar again only played from beginning. Seems an obvious glitch to me, but no recipe for reproduction. As the subject line suggests, it's random.

Sixfinger
Just an update..., working on the same project as I'm practicing my solo prior to recording.  Using the space bar to start play, no editing, no fat fingers, space bar only, there were several times it went back to zero. pressing space bar again only played from beginning. Seems an obvious glitch to me, but no recipe for reproduction. As the subject line suggests, it's random.

This is not new to X3d btw - I have had this happen in all of the X series SONARs. I often see this when looping playback and pressing the spacebar. The SPP Now time will go back to zero when pressing spacebar to stop the transport even though looping is enabled. Irritating - YES, showstopper - no.

groovey1

Kev999
It happens to me whenever I have been pressing the spacebar a lot to stop and start playback.  When it happens, pressing the spacebar twice will bring it back to the original position.
 

I've also noticed this fairly regularly. I don't know if it's related to holding the spacebar down longer than normal or what. It almost seems like there's something in there by design to allow you to go back to either the now marker or the beginning, but I don't know what it is.

This is what I have always put it down to.  Not at DAW at moment, but must have a play around later tonight.

For users experiencing this with Spacebar, it sounds like this is just a matter of having On Stop Rewind to Now enabled. That's the default in a new installation. I always have it disabled so the Now time stops where it is, and the Now marker updates to that location and Ctrl+Spacebar rewinds to the Now marker (notwithstanding that there's an issue with X3 where the Now marker travels along with the Now time during playback. ).  Note, this is not the same as Pause where both the Now time and marker stay where they are on stop. Pause has no default keybinding; I have it bound to Alt+Spacebar.