Tested with Build 3938:
Thumbs+ changes the InitialDatabase entry after the end of the program. So when restarting the entry is incorrect.
Only if you end the program without any changes e.g. Path, the entry stays correct.
Monitoring of Thumbs9.ini is necessary, if correct starting conditions should be present.
The easiest way to realize this is to use a text editor.
A selfcoded starter can automate this.
If different databases are used, it is probably more complicated, since only one INI is present.