I've go an NFS export for whch group permissions does not appear to be working on NFS clients.  For example, users are unable to switch into directories for which they have either R-X or RWX permissions by virtue of group membership. None of these users are close to the 16-group membership limit.  Nevertheless, enabling map-lookup-uid on the export does not resolve the issue.  SELinux is enabled but in permissive mode. Rootsquash is enabled.

I could use some feedback.  Thanks!