Some 4K content unable to play on TCL 75R655

Server Version#:9.6.11.11266-ce71ac07c-Plex
Player Version#:9.6 build 11
<If providing server logs please do NOT turn on verbose logging, only debug logging should be enabled>

My apologies if what I entered for server and player versions are incorrect. I have noticed that only on this TCL TV does Plex have problems playing 4K content. I have the TCL 65R646 and a Vizio P65-F1; on the former I use the native Google TV Plex app, while on the latter I use a Roku Express 4K+ and the concomitant Plex app. I suspect it might have something to do with the HE-AAC 7.1 audio because I have reencoded some 4K videos to just use AAC 5.1 audio and these files proceed to play just fine. It is frustrating that this TCL TV is the most recent model of all my 4K TVs and yet Plex cannot play some 4K content. I’d rather not use a spare Roku stick with this TCL Roku tv but I will if I have to. Or I can always install Jellyfin. My NAS servers are actually TrueNAS Scale ElectricEel-24.10.2.4, running Plex app version 1.43.1.10611-1e34174b1.