Unstable 4K playback - identifying the weak link

Alright, it’s a shame I was only suggested this thread after I had started this one, but here goes for anyone interested, it could be simply due to the audio codec of the source file. I’ll try different audio sources later on and see if it fixes the issue.

Side note to TV manufacturers, what’s the point of marketing 4K UHD TVs if none of them support DTS-HD or similar, ugh…