OK, some observations.
Solo4K enigma2 can't play the UHD video, what is compressed with H264. At the same time, 1080 resolution files it plays, when it is compressed with H264. If the first convert to H265, then it handles that. Can you fix it? I can send sample(s) *.mp4. All UHD TV-s (Samsung, Sony) can do it nicely, maybe you can fold this little failure for Solo4K enigma2?
As from SAT-TV the broadcasts come only with H265, then apparantly based on this? And some codec for H264 is missing or other such thing?