I have repeated testing with 18.104.22.1687 - but its still the same.
I have only MP3-files, and the issue is reproduceable.
But I think, I have now more informations:
1. I manually delete all MP3 files on the SD-card
2. Start MM and uncheck all syncs with sansa clip+ external SD.card
3. Maunally start "Autosync" (there is nothing to sync = OK)
4. I select a genre with 7 MP3 files to sync.
5. Maunally start "Auto sync" (the files are copied/synct to the sansa = OK)
6. Repeated "Autosync" about 5x (there ist nothing to sync = OK)
7. Unpluged the snasa from USB port (the sansa database is actualized)
8. Connect the sansa again to the USB port
9. Manually start "Autosync" (from now on with every reconnect MM wants to delete and resync the MP3 files
I have testet the same with the internal Memory of the sansa clip+. Unpluging and replug is showing no issues.