[CentOS] systemd automount of cifs share hangs

Running latest CentOS 7.5. Since I found out about automount unit files 
I've had mixed results using them to mount shares from my NAS. Lately they 
seem to hang if I touch the mount point, but I can start the mount unit 
without problems. I had it working months ago, so I'm thinking something 
changed in the systemd updates.

For each mount point, I have two files in /etc/systemd/system named with 
the path of the mount point and with extensions .automount and .mount, 
following the systemd documentation. For example, srv-dav-name1.mount and 
srv-dav-name1.automount to mount a NAS share to /srv/dav/name1. I can issue 
"systemctl start srv-dav-name1.mount" and the mount completes instantly. 
But if I start the automount unit and ls the mount point, the shell hangs 
and eventually, a long time later (I haven't timed it, maybe an hour), I 
eventually get a prompt again. Control-C won't interrupt it. I can still 
ssh in and get another session so it's just the process that's accessing 
the mount point that hangs.

Any suggestions on how I can debug this? I'm still new to finding the right 
log files. /var/log/messages doesn't show any errors like timeouts.