SDL MultiTerm 2021 - Terminology Database shows as greyed out and italic in Terminology Database Management View and only allows me to load input models (and not add, edit etc.)

I'm using SDL Studio 2021 SR1 and SDL MultiTerm 2021 SR1 ( and my file-based Termbases don't let me change input models (or filters, layouts, export definitions etc.)

MultiTerm 2021 - Greyed out

I am wondering whether the issue is related to the fact that my "Documents" folder is synchronised (see the physical name above). 

1) Any solution to it?
2) There is not a lockfile in the location in the Documents folder causing the problem (previously I had to delete .ldb files to get full write access to the file).
3) Does MultiTerm use any other location on the C: drive for .xml files or similar, as I wonder whether there is an issue with read/write access to another folder?

Thanks in advance.