I run into this occasionally but don't know why. Every now and then overlapping clips will trim the ends of other clips when sliding/moving them leaving a new clip where they overlap, especially when copying and pasting clips that overlap.
 
This is not intended behavior on my part.
 
Please help me make it STOP!
 
Thanks.

I had a similar issue a while ago. It still occurs, but very rarely. Not sure what causes it but I think it's something to do with what is occurring "behind the scenes" with lanes and comping. Sometimes I can make it go away by losing the project, or copying the clips to a new track.

Here's my original thread in this, complete with video sample:
http://forum.cakewalk.com/m/tm.aspx?m=3556917

So it's not just me.  It happens randomly at will since the X1 days. I thought someone years ago had a fix but wouldn't even know what to search for. BTW, I normally don't use Take Lanes but it may be occurring after I open and close them and then move things around.
 
A quick check reveals it does indeed happen when moving clips around from one Take Lane to another. But it was also happening in the main track with Take Lanes closed, so that may be a carry over from being in the Take Lanes.

The video link is blocked or unavailable:
https://www.youtube.com/watch?v=UO8yHwxj2g8&feature=youtu.be

Try the video now. I must have made it private.

I think if you're doing a lot of "experimental editing" that involves a lot of undo and redo functions then it eeens to occur more often. But I can't seem to make a recipe and it's rare enough that it's not an obstacle.

Yes, it's been reported many times under different names.
 
When I reported it (under the name "Slivers") a baker said they'd look into it, but so far it's still there.