Issue:
Samba shares fail to mount in Nautilus

Expected Behaviour:
Clicking on the browsed share in Nautilus, or entering in the
smb://server/share path in the server entry line in the Other Locations portion
of Nautilus should mount the share.

Problem discovered when upgrading from 4.15.5 version of samba files to 4.15.7 
tested on 3 separate machines, and they all exhibit the same behaviour.

Workaround:
using cli mount -t cifs //server/share ./locallocation

GUI Error reported in Nautilus is:
 "Failed to mount Windows share ; Invalid Argument"

Current remedy:  downgrading these files back to 4.15.5 fixes the issue
 libsamba-policy0-python3 
 samba                    
 samba-ad-dc-libs         
 samba-client             
 samba-client-32bit       
 samba-client-libs        
 samba-client-libs-32bit  
 samba-gpupdate           
 samba-ldb-ldap           
 samba-libs               
 samba-libs-32bit         
 samba-libs-python3       
 samba-python3            
 samba-winbind            
 samba-winbind-libs       
 samba-winbind-libs-32bit

Thanks
Stephen