FireTV playback of HEVC-10 content - problem

I have been encoding movies with HEVC-10 (h.265) for the past couple of years - my older content is MPEG-4/H.264 - I just noticed that movies in HEVC-10 will not play back properly on any of my FireTV 4K's, but playback on Nvidia Shield's seems to work fine. In this case I am using the Channels DVR Server (Windows 10, core i5-10600K) to playback to the FireTVs. The FireTV's will playback liveTV from the HDHomeruns and MPEG-4/H.264 movies with no issue. Symptoms are stuttery video. I am thinking that a recent software update may have introduced a problem? Anyone else noticing this?

Is the FireTV set to Settings > Playback > Advanced > Video Decoder: Hardware in the Channels app?

At least one was not - changing it to hardware fixed the problem - I'll check the others (I hope they are also set to software) - do settings get reset during a software update? I thought all my clients were set to HW decoding at one point in the past - thanks for the reply!

I'm having the same problem with playing HEVC content from Channels DVR to my FireTV 4k. Seems odd, but I can play the ATSC 3.0 channel just fine and any shows (like news) that I DVR for 30 minutes play without any issues. But if I record a 1+ hour long show and try to play it on the FTV it just spins and never starts. I can play the same show fine on my iPad or iPhone.

I have HW playback enabled on the FTV. If I change it to SW playback the show will start but it is extremely choppy (and unwatchable).

Is this an imported video? It must be in some format that is confusing the hardware decoder. Can you submit diagnostics after it gets stuck