Ubu 16.04 Samba Fails on ?'s

I have upgraded my two main machines from 14.04 to 16.04 and when I attach to my old Samba shares (still ruing on 10.04 and not changed) these newly updated machines caot locate files with question marks in their paths.

I used another 10.04 machine to attach to the same share and confirm that the server is doing its job. The 14.04 machines were also able to access these same files/paths previously.

Is there some Samba configuration I need to do on the client machines to allow them to parse the question marks (and presumably other "dangerous" Windows characters)?