So, your NFS4 shares can’t be mounted from other systems. The mount hangs, and you don’t see any reason for it.
Have you, per chance, recently set up a folder in your NFS share and used fuse or some other utility to make the contents of a zip file visible through it? Because I did… and it completely breaks the NFS export.
There does not appear to be a system-wide way to mount a zip archive to a directory for all users as of this writing. So, the only solution is to get rid of the mount and copy the contents out of the zip.