hp pavilion all-in-one-pc 24 k0020na hdmi in display issue

[_dash_]

I'm trying to use the HDMI in on the hp pavilion all-in-one-pc 24 k0020na to use the monitor as a TV when the computer is not in use. The HDMI connection from my satellite/terrestrial box is picked up fine, however it is like the display is constantly scanning for another input and dropping the HDMI in, the screen keeps flickering black. I have tried updating the BIOS and the display drivers wondering if that might fix the issue but it has not resolved it. The screen is unwatchable with the constant drop -outs. I have tried a few different HDMI cables to be sure that isn't the issue and also tested the TV box on a tv and it's working fine, so it has to be some sort of problem with the all in on. I have no display issues when it's being used as a pc. Any suggestions or ideas! Current BIOS version is F.20

[itsmyname]

@_dash_ -- is this your computer's motherboard: HP Desktop PCs - Motherboard Specifications, Brighton | HP® Customer Support

I see:  Back I/O ports

• (1) HDMI 1.4/ HDCP 2.2 output port
• (1) HDMI 2.0 (UHD); HDMI 1.4 (QHD, FHD)/ HDCP 2.2 (UHD); HDCP 1.4 (QHD, FHD) input port

So, that HDMI-input port should accept HTMI signals from your "source".

I do not know why you get "drop-out".