Thank you for the clarifications 
Very strange Magisk behaviour indeed. Did you by any chance enable Hide the Magisk app in the Magisk settings before? 
That wouldn’t explain the wifi, thermal and sound issues though…
Without logs we probably won’t be able to figure this out, not that it would help your situation anyway, sorry 
(I’m just curious).
That’s unfortunate, then there’s probably nothing we can do here, I hope your experience with support is better than others 