I happily run two external monitors from my Macbook Pro, one of these is a Toshiba TV and the other is an AOC 27" monitor.
Occasionally after the computer goes to sleep by itself, when I wake it up the TV as monitor won't recognize the computer. The Macbook Pro detects the TV, I can see it in the "arrangement" tab in the Mac's display control panel, but the TV screen shows "no video".
I've tried detect displays, but clearly this wasn't the problem since it's being detected, I've tried all the controls on the TV, changing the input selection, tried turning it off and on, unplugged and plugged the cables back in, put the Mac to sleep again and woke it up, etc.
The only thing that will get the TV to display the computer again is restarting the Mac. Then, everything works as usual.
So clearly something about restarting the Mac makes it recognize or send a signal to the TV, otherwise I'd think it was something on the TV side.
Not a huge problem but I dislike having to restart the Mac when I really just wanted to wake it up from sleep.
Macbook Pro 13 inch 2017
OS 10.14.4
Toshiba Cast TV 43L511U18
Output: 2 USB C adaptors to HDMI cables,
TV input: HDMI cable
Best Answer
I'm having success so far at least by trying this answer to a similar question posted in 2012. I wasn't looking back that many years because I thought it wouldn't apply, but it looks like the same problem.
Switching my TV to Thunderbolt Port 1 on the Mac seems to be avoiding the problem for the moment. Now using Port 2 for my other external monitor, but since that's a regular computer monitor, perhaps that avoids the same problem happening with it.