SMB folders occasionally show as locked

A client has 5+ Mac Pros running against a Windows 2008 server.

All has been working fine - they updated recently to sierra and now, intermittently, the shared folders show as locked

I've not been able to any rhyme or reason, for some people it'll show as locked for others not and then with nothing being changed it'll either show as locked for everyone, or open for everyone, or those that saw it as locked now see it as open and vice versa.