Resolution Issues Macbook Pro 2019 Dual Ultrawide Screens Dell U4919DW

[aja656]

Hi
I've got two Dell U4919DW monitors hooked up using a DP 2.1 cords to a Kensington SD5500T thunderbolt 3 docking station which supports two 4K monitors at 60hz. One of the monitors is running fine at the proper resolution 5120x1440 and 60hz refresh rate. The other monitor seems to be capped by the operating system at 3840x1080. I have two of the Kensington docks and they both do the same thing with the monitors. So I don't think it's an issue with the dock. The monitors have the same settings so it's not a monitor setting. When in mirror mode on the mac, the OS allows for both screens to have 5120x1440 resolution, when you take mirror mode off the resolution on one of the two monitors gets lowered to 3840x1880. Apple support was useless and a waste of 2.5 hours. Not even going to try to call Dell on this one. See attached screenshots of the various display settings depending on mirror mode vs non mirror mode. Please let me know what you all think it could be or if it is a limitation of the graphics card.

MacBook Pro (16-inch, 2019)
Currently using Big Sur 11.0.1
2.3 GHz 8-Core Intel Core i9
AMD Radeon Pro 5500M 4 GB
Intel UHD Graphics 630 1536 MB

 

[arche3]

I think you have to have each monitor on its own thunderbolt bus. So 1 hooked up left and one right of the laptop ports. If you use xdr displays that's what you have to do. The 49 while not 6k still pushes a lot of pixels.