is your cable a HDMI 2.0? if its an older cable it doesnt support 144hz over HDMI
did you enabled highest HDMI version in your monitor? (Menu in Monitor)
did you installed the driver for your GPU?
1. disable Win10 auto-driver-install
2. install latest AMD driver
test again ;)
PC: R7 2700X @PBO + RX 580 4G (1500MHz/2000MHz CL16) + 32G DDR4-3200CL14 + 144hz 1ms FS P + 75hz 1ms FS
Laptop: R5 2500U @30W + RX 560X (1400MHz/1500MHz) + 16G DDR4-2400CL16 + 120Hz 3ms FS