I'm still not sure how it was working before, but it's working after I replaced the WD19S with a WD19TB.
I have a Precision 3541 connected to a WD19S dock that has two S2721DS monitors connected to it. Currently one of the monitors will run at 2560x1440, but the other will only run at a max of 2048x1080. Both monitors were running at 2560x1440 up until I opened open the laptop to use as a third display. After noticing that caused the problem I tried disabling the laptop display in Windows, but the problem still persists. I have updated both the graphics drivers and the docking station firmware. Any suggestions would be appreciated.
Precision 3541 and WD19S docking station 2nd monitor lower resolution