Im having the same issue with brand new RX 6750xt
The minimum frequency workaround does not work on my system and the audio cut opff happens every 2.4 seconds. Looking at receivers screen, it is as if the audio keeps reconnecting over and over again. I tried with on-board vega as well and it also happens there but much less frequently. Sadly i cant use that audio as windows always puts it as display 1 and then i cant see anything since RX is on display 2 and it only show extension of desktop and while it can be cloned, it only works until i restart the computer.
I dont know which is to blame here, but this really needs a fix.