[Zubersoft]

Unfortunately, I restored your library, connected the companion app to my Android tablet, deleted every MUJ Songbook song, saw no issues and the files were properly deleted on my device. So I'm not seeing a problem with the library you provided or the companion app. You can try uninstalling and restoring your own backup file to see if this gets things back into a good state. I'm not sure what else to recommend.

Mike