[Vibraphon]

So the problem appears to be with the companion backup functionality?

Yes, I think so.
It was the first time that I did changes using the companion connected to the tablet. I think, the only way to lose files was during backup the changes to the tablet. May be the reason is the way I did my changes:
I selected several files in the companion because I wanted to changed one parameter value for all selected files.
Each time after changing one songs data the cahnges were written back to the tablet befor I could change the next songs paramter.
I think that my backup-file is too big to save in short time, So I think data get lost during backup.

To my oppinion it would be better to make all changes in the companion on the PC-Ram and then backup all changes at once to the tablet.