Just tried PMS 1.14.1.5487 and have mixed results. Some TV channels now stream via the AppleTV, yet others will not. I can’t seem to distinguish between them. That said, some times it takes several stop and starts (eg start a channel, wait for it to spin several times to load, cancel, start the same channel again - and repeat) for the channel to stream. At this time, similar to other times, streaming via the PMS web client and using a third party app worked first go.
It’s just unreliable that I’ve gone back to 1.13.8.5395 again and am happy streaming TV.
Since last post, the Apple TV Plex client has auto updated to the latest as I am now using the updated player.