high sierra external monitor black with mouse

I just upgraded to High Sierra 10.13.2 on my macbook pro 15 inch mid 2014. I was disappointed to find that not all of my external monitors work now. I was running Sierra and pleased with the multiple monitors as below.

Yes, 4 external monitors is a lot, but when the alternative is very expensive large screens and several 24 inch monitors are available, it works out well (at least it did)

Now all 4 monitors are recognized and in the same arrangement, but 2 of them are black. I can see the mouse when it moves over that portion of the landscape, but I cannot see anything else. When I do a screen capture of the region, something is saved to the screen shot, though.

If I close the lid on the macbook, one of the black screens turns into a black screen with a blinking cursor.

I tried resetting the NVRAM and that made no difference.

Any ideas?

Thanks in advance.