Sounds like it could be a difficult RF environment causing it, but then again, it's not like the APs or the TVs are moving. The RF environment can still change of course, the trick may be finding what other variables we have since the equipment is stationary. Where are the APs in relation to the TVs and what is in between them? How often is the pixelating an issue, is it fairly frequent, or any particular rhythm to it, or it's only on occasion and completely random?
Also curious that all 3 APs landed their 5GHz radios on channel 44 when the RF profile is set for auto channel. You're close enough to DCA there's the radar question, do you have DFS channels enabled? And if you look at each AP's list of clients, what are the client TVs actually connecting to, 2.4 or 5? When you look at the TV's client page, what are its capabilities and SNR?
Perhaps toggle a few things such as making the SSID 2.4GHz vs 5GHz only for a period of time, and on the 5GHx side perhaps manually setting 20MHz channels and manually set 3 non-DFS channels like 36, 44 and 153 for example.