TV turns black for 3-4 seconds

I have a strange thing that’s happening in my family room. I have an H96 Pro Plus, connected via video switching on a Marantz SR6009 to an LG 79UF7700 4K TV. When playing 4K MKVs only, I will randomly get the screen going blank for 3-4 seconds… This will happen maybe a dozen times during a movie, but it seems to be random. I switched the H96 for a different unit from another room and the problem persists. I’m running CoreELEC 9.0.1. In other rooms, where the H96’s are connected to Sony TVs and no separate receivers, the issue doesn’t happen. It also doesn’t happen ever with 1080p videos.

Any thoughts?

I forgot to mention. I used to have an Amazon FireTV Stick 4K on this TV, and it played the 4K files fine via a side-loaded Kodi. The only reason I switched was that Kodi was constantly crashing on the stick.

There could be two reasons for this:

  1. You need a proper HDMI cable (premium certified)
  2. Try a different HDMI input on your AVR or TV

I had the same problem with my setup.
I changed all HDMI cables with premium ones. This decreased the blackouts, but not completely.
After moving the HDMI input on my AVR closer to the HDMI output, all problems were gone.

You could also try to connect your box directly to the TV to see, if your AVR is the problem or the TV.