LibreOffice 6.1 won't open files over cifs network share on Ubuntu?

I have some file stored on a Network share which I have mounted as as a drive on my ubuntu desktop.

In LibreOffice 6.0, it would open the files, but keep me in read-only (pretty sure due to a network permission which I have not fixed).

In LibreOffice 6.1, it won’t even open the file. It just says ‘access to {filename} is denied’

However, If I copy and paste the file to my desktop, it opens fine.

Any ideas?

What protocol is the share mounted as?