Both my Firestick Plex applications cannot access my server and they do not issue a code to activate

I updated to 1.12.3.4973 and now neither of my Firesticks can find the server (all devices are on the same LAN segment). When I logged out of the Plex app on the Sticks and attempted to sign back in, they show the http://plex/tv/link page but do NOT issue codes.

How can I rollback to a working version of the Plex Server application?