Does this happen with all video modes or only with 4K?
Thanks for the quick response. I decided to do some troubleshooting on the hardware side of things and it would appear that it "may" have been the HDMI cable that was the problem as I'm using another one just now and the issue has not yet re-occurred after playing a 4k video for about 6 minutes now. Strange, as the HDMI cable I was using works fine with other devices and there was no issue with it on previous build I was using. I'll report back if the issue crops up again but hopefully it's now resolved. The 4k HDR looks fantastic btw; nice work!
Update: The problem has indeed re-occurred, I'm afraid. I've tinkered with the display settings and the intermittent blanking of the screen does not seem to occur at all if I reduce the display to 1080p in the Kodi's display settings. If the display settings are set to 4k then the intermittant blanking happens even when not playing video, it happens when navigating Kodi's menus too. If I play a 1080p video though it does not occur, even if Kodi's display settings are set to 2160p as evidently it reduces the the resolution to match the video. Definitely seems to be an issue with displaying in 4k.