A MIDI part disappeared after reopening project

A MIDI part on an instrument track randomly disappeared after reopening the project this morning. It has not shifted or copied to another place. It’s just gone. The track is empty.

I went to the back up files but the MIDI part is also missing from them, even though it was present when I worked on the project last night. This has never happened to me before. What to do?

Sounds like there are Track Versions on that track.

I don’t think so. There is only one track version (v1).