It's driving me nuts

For no reason I can see, my midi parts get sliced up, I’m not aware of doing any thing to make it happen. I start out with a number of midi parts. After a while I notice that they have been split up. In the attached screenshot it happened at the beggining of bar 3. This is just an example. The split could happen anywhere on the timeline, but all of the parts are always split at the same point.

Is this some “feature” I have inadvertently turned on? I’m sure the answer is obvious, I just can’t see it.


To me it looks, like you hit Alt + X by accident (when the cursor was at bar 3), what means “Edit > Functions > Split at Cursor”.