LG B2 locked at 4k 60fps, reverts to 1440p when set to anything >60hz

Hello, i recently got a pc that is capable of outputting 4k 120fps/hz. The issue is when i click 120 hz when im at 4k, the tv reverts to 1440p 120hz and whenever i try to go back to 4k my hz reverts to 60. Im using an hdmi 2.1 cable and plugged into hdmi 4 which is one of the HDMI ports on this tv that supports hdmi 2.1.

Im completely confused and disheartened, since I could’ve bought a PC $1000 cheaper if i wanted to play at 1440p 120hz. Any suggestions?