Yes, I have used BETA, but quite long time ago. I was not using BETA for some time, now I installed final version directly. Should I delete everything on my.avast and Google Drive, then uninstall Mobile Backup and re-install it again?
Edit: seems it worked, at least backup goes without duplicates and so on. I will try later to delete one contact from the list at my.avast.com and I will check if app will detect it.