As I mentioned in an earlier thread, sometimes certain functions suddenly stop working.  Case in point: Split Clips.
 
I was editing a vocal today and splitting clips tso I could zero in on a pop.  I edited several clips successfully.  Suddenly, the split tool stopped acting like a split tool and started acting like a cursor.  Clicking on a clip would not split the clip anymore.  Double-clicking with the split tool would open Loop Construction.
 
The only fix is a complete reboot of Sonar (not just a reload of the project).
 
It is hard to believe this doesn't happen to others.  Anyone experience this?
 
Note that other functions like Cut, Copy, and Paste sometimes stop working as well.
 
Thanks.

Make sure the focus is on the clip not an envelope. Shift click on the clip header until it takes the focus. Alternatively change the selection on the track header drop down to clip.

Thanks, but to clarify, what happened today: split a clip, split the same clip in another spot, split the same clip in another spot, try to split the same clip in another spot and it doesn't work.  Now the scissors won't work anywhere.
 
Reboot Sonar and go back to the same clip and split works again.

I've had this happen if I'm using the Smart Tool+Alt and trying to apply split to either a mono clip that was converted to stereo, or vice-versa. Choosing the dedicated Split tool solves the problem.
 
There are some circumstances where the split tool doesn't work on a clip because it's not a "real" clip. For example, if it's being processed by V-Vocal as a Region FX you can't use the split tool.

if it happens again, try and remember what you were doing up to the point this started happening nd maybe we can figure out why it happen :-)
 
best with this.
 
Chuck

Another possibility is that you have lanes open (perhaps with only one lane) and are trying to split the composite (track view) clip which won't work. Although unlikely if you've only just split it elsewhere, but if there's a bit of time between splits and that would be fairly easy to do.

Did the splitting of the clips create any orphaned notes (notes which extend either side of the split point)?
 
Sonar 'goes a bit mental' in this circumstance.  It just doesn't handle orphaned notes at all, i.e. I do not think any code has been written to explicitly manage this.  I say that because the software makes no attempt to ask any of the pertinent questions to the user which it should: "Do you want to truncate the note(s) to fit within the new clip, split the note(s) between the clips, or extend the clip(s) to incorporate the orphaned note(s)?"
 
I've seen Sonar exhibit really bizarre behaviour when creating orphaned notes by splitting clips.

Have you checked your snap settings? The only time I noticed this is when I had "snap to markers" engaged and set to snap to clip edges. I would try to split a clip and it appeared to not work, when in fact it kept "splitting" at the edge of the clip.

I've had the same issue. Always figured it must've been some button I hit, but it annoys the hell out of me. It's not frequent, but seems to appear randomly when I've been working on a project for a while. Rebooting Sonar always works but it's a really dumb embarrassing thing to do when you're not alone.

ston
Did the splitting of the clips create any orphaned notes (notes which extend either side of the split point)?
 
Sonar 'goes a bit mental' in this circumstance.  It just doesn't handle orphaned notes at all, i.e. I do not think any code has been written to explicitly manage this.  I say that because the software makes no attempt to ask any of the pertinent questions to the user which it should: "Do you want to truncate the note(s) to fit within the new clip, split the note(s) between the clips, or extend the clip(s) to incorporate the orphaned note(s)?"
 
I've seen Sonar exhibit really bizarre behaviour when creating orphaned notes by splitting clips.

OP's talking about audio clips, whereas it appears you're referring to MIDI. I don't want to hijack the thread, but I'll just say for the record that I'm not seeing a problem with splitting MIDI clips. What you get depends on the setting of Non-destructive MIDI Editing in preferences:
 
- With it off (my preference), SONAR will leave any notes that cross the split in the earlier clip, and the later clip will start with the first note after the split point. In this mode, the sound of the track is totally unaffected by the split. Initially it will look like the clips are overlapping in the same lane, but after toggling lanes, the later clip will be shown in a new lane.
 
- With non-destructive MIDI Editing enabled, the notes crossing the split get truncated by slip editing, and the later clip contains only notes that start after the split as before. The reason it's non-destructive is that either clip can be slip-edited back across the split to restore the full length of the truncated notes. But unless you move the split to a point where no notes are truncated, the track is going to sound different. I usually want to preserve the sound above all else, which is why I prefer the "Destructive" mode.