Thanks for the responses, guys. It’s weird, as of this morning, it’s been working just fine, so I’m not going to mess with it.
Merlin, thanks for the info. I will try that if it stops working again.
Graham, even when it wasn’t working, monitor 3 was always checked. If I checked monitor 2, then went back into preferences, it switched back to monitor 3. But still no output. Weird.
Well, if all else fails, I do have a T-Tap on my other system that I can steal temporarily. But I use the third monitor on this system as a computer monitor for other applications, which is why I’m trying to get this setup to work.
Thanks again for the responses.
Keith
MacBook Pro (2018)
High Sierra