Some other things to try:
- Use a newer hdmi cable, really. Sometimes older cables may not support newer hdmi/hdcp/hdr standards, or it could just have a busted pin that causes weird hdmi handshake issues.
- Update the TV (software) itself.
- Change some display settings in windows, on the TV, or both. For example:
- set resolution to 1080p/2160p
- set refresh rate to 60hz/120hz
- turn on/off HDR
- Does the TV show up as a display in windows, even when showing no signal? Then try waking it by changing the resolution, or setting it to disconnected and back
- Instead of restarting your whole computer, try restarting your graphics drivers: Win+Ctrl+Shift+B
- Reset your external display settings to force windows to 'rediscover' a particular display device. To do so, delete these three registry keys. Warning: this applies to all displays:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Configuration
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Connectivity
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\ScaleFactors
Hope this helps. For people trying to avoid weird hdmi issues, pay attention to the supported hdmi versions of each device. 2.0a, 2.0b, and 2.1 each behave a bit differently. Going up or down version steps can involve some jank, and HDR, and/or 4k+120hz are especially temperamental.