Refresh rate external monitor at 30Hz instead of 60Hz

Hi, I recently bought a new monitor to connect to my iMac. It is a 4K monitor from Philips, the Philips 276E8V. I also bought a cable that supports 4K at 60Hz but weirdly enough I can't get the refresh rate to 60Hz. When I lower my resolution in system preferences I can get it to 60Hz but there is no way for me to get 60Hz at a high resolution. I have tried everything to get it to work but I can't figure it out unfortunately. The cable states in the product description and on the back of the package that it supports 4K at 60Hz, so it should work. I also tried to fix it with SwitchResX but that didn't work either. Is there someone that has another solution that might work?