Cox Contour and 4K TVs.

So, they say there is a known issue with Cox and 4K tvs, where you either get a no input error or, for me, just a black screen.  When I reboot it, it normally won’t display anything past the Welcome screen, then goes black.  After some troubleshooting, they ask if I want a service tech to come out.  Not sure how this will help, if it is a known issue, but why not?  After a box swap, cable change and lots of resetting, it eventually starts to work.  The same thing sometimes happens eventually after an hour or so of resetting and cursing on my part.  Now, a few days after the tech, it’s doing the same thing.  Do I just have to switch back to At&T?  Anybody having the same issue?