[GNA]

Fortunately, I managed to figure out the problem. The session bars were not lining up with where I expected them to be based on where the bars ended in my MIDI notes.

The MIDI notes had become weirdly offset and partly overwritten by some editing. I'm not sure of the cause, but sometimes when I'm trying to copy and paste blocks of bars or do certain edits, this kind of weird magical "warping" occurs, and the paste gets misaligned or overwrites the wrong bars.

It's kind of a misalignment of a whole section of a track that's been pasted, even when I've got the grid, cursor and tools set up properly and things should be locking and pasting pretty easily. At any rate, I usually catch it when it happens, and I just undo and correct it, but I didn't realize it had happened again this time.