[NAME]  Sounds like the WD19TB when connected to your 7490. is running in USB-C backward compatibility mode rather than Thunderbolt mode. There are two possible causes. One is that your 7490 doesn’t have Thunderbolt, since it was optional on that model (but was standard on the XPS 15). The other is that you don’t have the Thunderbolt software/drivers installed. If you don’t have Thunderbolt, you can’t run dual QHD and USB 3.x over your USB-C port at the same time, and any dock would set up USB-C to run USB 3.x. In that case, you can either:
I have a WD19TB Docking station with 2 Dell Monitors (S2721DGF & S2719DGF). When connected to my 7490 laptop, I can only get one monitor to display 1440p. The other monitor defaults can only max out at 1080p. I've connected the docking station with my XPS 9500 and can get both monitors to display 1440p at the same time. I've connected both monitors with DisplayPort and tried 1 DisplayPort and 1 HDMI. Is the 7490 able to capable of 2x 1440? The graphics is UHD 620
7490 - Problems with 2 External Monitors at 1440p