Hey Everybody!
Same issue here!
root@blade1:~# pvesm add nfs bart2test --path /mnt/pve/bart2test --server 10.0.34.206 --options vers=4 --export /mnt/bart2/nfs/
create storage failed: storage 'bart2test' is not online
root@blade1:~# mount.nfs 10.0.34.206:/mnt/bart2/nfs nfstest/ -vv
mount.nfs...