So I changed the timing standard to CVT - Reduced Blanking, the refresh rate to 120Hz, and kept the resolution at 3440x1440. When I set it from 100 to 120 in an attempt to make a custom resolution it changes the G Pixel Clock kHz value from 543600 to 652320. I cannot apply the setting as there is an exclamation point beside 652320 (below)
View: https://imgur.com/v3Ns2bk
The only way I could save the custom resolution profile was to revert that number back to 543600 while keeping 120Hz in there. It saved the resolution setting in windows but the screen stayed black so I had to wait for it to revert to 100Hz to get my screen back again. I am at a loss, I really think it might be the cable that came with the AW3420DW at this point although that would be disappointing.