I have an idea for you (assuming that you haven't done all of these things already):
- Download DDU, read the instructions and run it.
- Download & install the newest X570 Chipset Driver Package.
- Download & install the newest Adrenalin Driver Package.
- Restart your PC.
- Try setting your fan speed in Adrenalin again.
If this doesn't solve the problem, then you should contact Sapphire about an RMA because these steps would've completely fixed any software issues involved.
Setting fan speeds in Adrenalin doesn't cause problems, it's as easy as pointing and clicking. If there's a problem with that, either the Adrenalin software installation is corrupted (which is most often caused by not using DDU before installation) or the card is reacting badly to the instructions that it's receiving from the drivers (which means the card should be sent to Sapphire for an RMA).
I threw in the idea for the chipset drivers because
almost nobody ever thinks of those. Neglecting the chipset drivers can also cause weird problems so even if that's not causing this, updating them is still a good practice to have.