Just to add to the list of strange stuff that happens in applications of any complexity:
I opened a project and Cubase reported that an audio file was missing.
Minor old project so I wasn’t surprised nor concerned.
The missing file in the project was edited in Melodyne as ARA2.
Now the part was empty and the ARA logo was still in the upper right corner of the part.
I tried to “remove the extension from selected events” and was greeted by the "A serious problem has occurred. Please save … " that we all know and love.
I kind of suspected this to happen and said “Uh-oh!” already before clicking on the command, so …
Now you know!
Put a plug in the hole and gaffa over it.