I'm having the same issue today. Montana PBS coming in solid, 12180 mux nowhere to be found. Not even showing in a blindscan. I watched it last night without issue and it's clear today. I guess they must be lowering the power sometimes. Or we're both having a bizarre equipment failure.
I get the feeds bouncing from 0% to barely anything then back to 0%, thought it was a tree but considering how many other people are having issues, something is probably going on.Having the same problem as you..