Freesync works for me with that cable, but I have some awful cable training problem or something. Everytime the screen is reset, it refuses to go above 4k60 or turn on freesync, and it'll only work again after I have the screen connected for a few minutes. So whenever I start my comouter, have to switch down 4k60 and wait like half an hour to be able to use high refresh rate. It's been doing this for months.

I don't know if I have a bad cable, weird interference, or if FRL adapters are just flaky.