DVR will not record! "ERROR - Couldn't check for the existence of file"

I’m certain this has been asked, so I apologize in advance, but I have been unable to find it.

I just moved from Windows 10 to Ubuntu Server 16.04 LTS for my Plex server. Everything is working great EXCEPT the DVR. The tuner is recognized, I can watch live TV (through Plex), and the guide is populated, but recordings fail each time. The gui reports “No write access to destination”

Checking Plex Media Server.log I see the following error lines:

Dec 12, 2017 10:01:20.111 [0x7fa8e4bec700] DEBUG - DVR:Grabber: Saving recording to /mnt/plex/Videos/Television/.grab/024b2e91403bf066c2d96acb4764eb4cfe3ac276
Dec 12, 2017 10:01:20.113 [0x7fa8fa1e4700] ERROR - Couldn't check for the existence of file /mnt/plex/Videos/Movies/.grab: boost::filesystem::status: No such device: "/mnt/plex/Videos/Movies/.grab"

/mnt/plex is a CIFS share on my NAS.

Any ideas? HELP!> >