At first the game wouldn't run at all. After I updated my Nvidia drivers, it still wouldn't run (won't start... get a black screen and then back to desktop) on my native resoltuion.

So i switched my desktop resolution to 1920X1080 and the game ran (albeit sluggishly considering 8700KCPU and 1080 GPU... is this thing optimized at all?).

I switched the in game resolution to 2560X1444, quit, reset my desktop to it's native 2560X1440 resolution, and... same thing as before. Game won't start... get a black screen then back to desktop.

The game should run fine on your system. I ran it in Bootcamp on a 14,2 Imac with a 780M. using the steam version.

Are you runing windows 10 or earlier?

If you are running Windows 7 make sure the driver is at least 430.64
Currently using 431.60 without issues with a 1070.

Try to upgrade your drivers to the last version. Worked on my second PC.

Intel Core i7 8700 (non-K)
nVidia GTX 1080ti EVGA FTW3 (Device Manager, Properties, Driver Version: 26.21.14.3160)
3840 x 1080 Super Ultra Wide res display
Win7 x64 machine (older games need to run)

60 FPS to 30 when it dips depending on what's on screen.
Fullscreen, bordered, borderless, everything works.

But compared to the pre-BEYOND version, the game is stretched, and some HUD-layer elements are a bit wonky (loading screen, star system names are not actually tracking stars), but the "HUD" HUD itself, ingame, seems fine.

Maybe you have to set the right resolution in the video settings.
My system is set to 2560x1440 and the game used not automatically the same resolution in full screen, so it used a wrong streched resolution.

BTW, absolutely no problem to start from 1440p, as th OP described.