In the MIDI Editor, if you try to edit the left edge of notes in a MIDI item that is looped such that the first iteration of the loop doesn't start at the beginning of the item, the note gets shifted to the right, and set to zero length.
Steps to reproduce:
1. Create a new empty midi item, with source looping turned on
2. Draw a note in the middle of the item
3. Drag the left edge of the item out slightly so that the note is not visible in that section
4. BUG: Drag the left edge of the note
Observed behaviour: The note is corrupted
Actual behaviour: The left edge of the note is trimmed out.
See attachment for a project file that demonstrates this issue.
Tested on Reaper v6.02 64-bit on Windows, portable install.
Not gonna lie, I was pulling my hair out about this, I had a lot of loops with pickups, and any time I try to adjust the note attacks, they would just disappear