Well heres my opinion, the TV signal may not be not compatible with the sync from GPU or a bad/old hdmi cable.
That motherboard and GPU should have no problem with that, have you tried another display output, a real monitor. And how about a DP link between the 2 devices…just saw it… a 4k with no DP ports…shame
Use the latest GOP updater on the forum:
AMD and Nvidia GOP update (No requests, DIY) - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum (level1techs.com)