I'm the sort who never upgrades until forced to and this is yet another example why.
I had several machines on TV12 and whatever iOS version worked with them and all was well. The other night when TV central was apparently down but the website claimed they were up I decided maybe I ought to switch to 13. Bad move. One of the machines is a rather ancient Dell running XP Pro SP3 with a 1280 x 1024 display. I can TV into it just fine. But when I want to TV from it to another machine which is running Windows 8.1 with a 1920 x 1080 display I get no image from the other machine. No error message; just no image. It comes up but is solid black. I've tried the various settings at the top of the display. Any ideas? It's nothing critical; inbound, which does work, is more important than outbound but it's too bad it no longer works as it used to.
I was just about to click to post when I decided to do a further experiment by connecting to a Windows 8.1 laptop from the ancient Dell. This one is 1366 x 768. Same thing...I only see a black screen. As it is in view I did see that mousing around on the ancient desktop did make the cursor move on the laptop. But the reproduction of the laptop's screen on the ancient dell stays black.
I don't think it's the differing resolutions but something else.