Cannot use 2 x LG 5K monitors in Ubuntu 20.04 ARM, only 1

I just hooked the second 5K to my MBP M1 max. FYI, they work if set up as 4k monitors in Ubuntu, but this is far from optimal.
The Parallel tools have been working since the beginning and have been updated. I even tried to give 32GB memory to the guest Ubuntu, but that didn't solve the problem. Is there some VRAM limit somewhere?

When I managed to get the rest of the setup solved, I got a reasonable error message from Ubuntu when I tried to switch from 1 monitor to 2 that :
"This could be due to hardware limitations.
What are the limitations? Is there an option to give Ubuntu more VRAM or something? I have 64GB system memory.

Thank you for any help!