Precision 7530 + WD19DC triple display issue

We recently purchased several Precision 7530 and WD19DC docking stations with the intent on using them with triple displays. We're using this with Dell 27" displays with a native resolution of 2560 x 1440.

Unfortunately we're only able to get 2 out of the 3 monitors to display at this resolution. The third monitor won't go higher than 2048 x 1152. All monitors are plugged into the docking station using the 2 display ports and 1 USB-C port. We've made sure all drives are up to date.

According to the WD19 User Guide, it looks as though this hardware should be capable of outputting 3 @ 2560 x 1440. Any thoughts as to why this isn't working?

EDIT: after a bit more digging around, I found we needed to enable "Graphic Special Mode" in the BIOS which enables discrete graphics. Process is described here, though the option was labeled a bit differently for us. After enabling, we're now able to display 3 @ 2560x140.

Thanks!