Just for more experimentation, you might want to check against one of my NFS mounts (no such problem seen yet):
In /etc/fstab:
nas1:/mnt/musik/Musik /home/matthias/Musik nfs users,noauto,nofail,async,noatime,_netdev,x-systemd.automount,x-systemd.device-timeout=10s,x-systemd.mount-timeout=10s,retry=1,x-systemd.idle-timeout=10min 0 0
I suspect maybe because I use _netdev. Excerpt from man systemd.mount:
_netdev
Network mount units are ordered between remote-fs-pre.target and remote-fs.target, instead of local-fs-pre.target and local-fs.target. They also pull in network-online.target and are ordered after it and network.target.
See also Automount NFS share on access, again.
Another hint: Using defaults is mostly a bad idea, and sequence in the options field matters.