On TWO working systems (desktop and laptop) I have the same issue.
When I start rpc.idmapd I receive the unclear error:
make sure DNOTIFY support is enabled
DNOTIFY is enabled.
If I run:
rpc.idmapd -f -vvv
the error is:
Unable to inotify_add_watch(/var/lib/nfs/rpc_pipefs//nfs): No such file or ...