Try lowing the RES/VIS to 1920x1080P with 16X For Texture instead of pushing it at 4K for this game.
Make sure though the Monitor and GPU/Graphic Card both support the RES or VIS = Visual Image Size. Never a good idea to max GPU/Graphic Card unless your system can handle it. The game here I run it at the max well my GPU/Graphic Card is rated at 2560x1600.
See if that solves your issue. How much RAM you have? Are you sharing RAM or using GPU/Graphic Card in one of your MOBO = motherboard slots?
Monitor VIS (visual image size)? 23, 24 or higher?
Well, i could imagine that this game will have A LOT of problems playing in on a 4k system.
I dont even think your videocard will handle propertly it in full screen, no matter how powerful it is (the game is not really good optimized).
About the tiny fonts, you cant do anything about it. It is one of the cons of playing this game in such big resolutions.
As the mate said, try to change to a standard resolution (1920x1080 is far more than enough) and if the problem still persists, well, maybe is something related to your videocard drivers. One thing, is your videocard present in the list of videocards when you go to the display options?
So the software sees your GPU/Graphic as you say. You are aware of the issues with 4K on desktops systems.
Refresh rate 60Hz on 1080p but with 4K since it's so demanding on system it can't always do 60Hz and then throttle downs to 30Hz. You'll never see frame rates go above 30 fps.
Windows suffers from scaling issues with pixel density hits 200 pixels. Anything lower than 30-inch 4K Monitor will produce 146 PPI thus using 24-inch same res hits 184 PPI. Thus making icons and web surfing pages look weird.
What size monitor are you using or did you get both 4K PC and 4K UHDTV to use a your computer monitor.
That 4K GPU is it dual core with dual 4GB(8GB) VRAM.
Also have you lowered the RES/VIS to 1920x1080p as I had suggested? What was your final results. I know some people here run this game at 1440p but those systems are mostly homemade type of tech builders. 4K is so new and down the road 8K is only use in commercial sources. Super-UHD.
Anyway if you care to share your setup, which will help those who use 4K desktop shed some light on your issue with the game and your 4K system.