Hey, that sounds frustrating. I’m not familiar with this specific issue in the manner that you’ve phrased it, but I’ve heard of a digitakt forgetting what was done in the most recent session after being powered off and then back on, or also perhaps loading into the wrong project even if a proper save was performed. Not quite what you described though.
You can take a look in the bug reports thread for a report of something similar, because sometimes those issue reports are followed by discussion about solutions etc.
Might be a good idea to add some details to your opening post like which OS version the digitakt is currently running and whether or not the project that normally contains those errant samples is completely unimpacted.
I would take a look at that other project and any other projects and make certain that something wasn’t inadvertently saved over with a different name.
If I can think of something else, I’ll let you know. Maybe someone else here will have a suggestion.
Good luck