AppleTv cannot play media files - loading icon spins forever



I recently updated the Mac Mini that runs my PMS from Mavericks to High Sierra and PMS version, & a system that had been stable for 2+ years started having problems with my 2 AppleTV devices. On trying to play any media files the icon just spins forever. The clients on my iPhones and iPads and the web clients on my Macs work well (in fact better than before with no skips) but both my AppleTVs show the same behavior on any media file that I try. The interface shows all of the metadata correctly and even know where I left off watching the media on another device, but when I press play the icon just spins forever.

Here's the details:

AppleTV Model A1625 (32GB)
TvOS 11.3 (15L211)
PlexApp 1.26 (8506)

A zip file with verbose log from the AppleTV and the PMS log and database attached. There are some errors in the AppleTV log but I haven't been able to find out anything about them.

Any help would be much appreciated.