iMac HDMI output
I have a pretty new iMac Pro running latest Mojave. Two weeks ago I bought a 32 in. Vizio TV to use as a secondary monitor when I do a live stream. The software allows fore a Program Out to a second monitor. I plugged in a USB-C to HDMI cable from the Mac to the TV. Everything worked as it should. The second monitor showed up in ARRANGEMENT and a desktop image showed up on the TV. I used this for the live stream program monitor. Put the TV away until two days ago for another live stream. Hooked up the TV and TV said: NO SIGNAL ON HDMI INPUT. Tried three other cables. Same issue. Called Apple. After 30 min. she said "call Vizio". Well.. I had plugged in the HDMI out from a GoPro to the TV and it worked fine. So it's not the TV and I confirmed that with Vizio. This morning I spent another hour on the phone with a senior tech to no avail. He gathered a data dump and is sending it in.
I'm totally stumped. The computer sees the TV in the ARRANGEMENT window and when the tech was screen sharing, he could see a desktop image when he moved the cursor to the other monitor's position. I see nothing on the TV other than "no signal".
Any suggestions from he smart people online would be most appreciated.
I have nothing connected to the Mac other than the TV. No firewalls, weird extensions, etc.
Thanks
iMac Pro, macOS 10.15