Mojave won't properly recognize QHD (1440p) external monitor.

I've been using this monitor (BenQ EW2780Q) with my MacBook Pro (2016) with no issues for the past few months. The monitor is a native QHD (1440p) monitor and I was able to get the full screen resolution.

Then today, when I logged in, macOS is insisting that the "Default for display" resolution is 1080i (fuzzy screen and all). The actual native resolution is not present in the list of options (even when I `option-click` on the "Scaled" radio button in the Displays preference pane).

I'm confused because it was working just fine, and now it's not. Can anybody please suggest anything I can try? Losing all of my screen real estate is driving me nuts.

Thanks!