Same here. I have reinstalled several times, cleared data, allowed access to memory.
I somehow made it work...
I uninstalled TB.
In solid explorer I searched for titanium and also titaniumbackup and deleted everything in root and internal memory. I think I found 5 files.
I unticked "automatic reinstall" or what it might be called in English in settings (only doing this did not help)
I then installed TB from Playstore.