I can now change lighting on my RTX3080 after update but GPU is not showing under synced devices and I am sure it used to. BUT is showing under 'Device' ...... strange, the good new its not a rainbow any more. 

I have ASUS Rog Strix RTX 3080 - the same! It is stuck on rainbow and - no page. I reinstalled and no change. Just had an update from ASUS as well ands you guessed it no change. Everything Blue except the GPU which is in rainbow colours.