Could your feet be extra sweaty?
Good pacs can be very warm, and with moderate activity generate more sweat eventually wetting out insulation. Tried changing into fresh socks? Or try the bread bag over sock see if makes a difference?
Pacs are warm but subject to sweat. I’d look hard at the Hoffman or the cabelas trans Alaskan, the later vents better than most.
Maybe you should consider looking at the white surplus “moon” boots. Very warm and if you sweat they are a vapor barrier and no heat leaves even tho your feet will be wet, but usually not cold. If you go that route, whites size down 1.5 from your size.
In any of my pac type boots if I’m active I wear cotton, yes, to absorb my sweat and change into wool socks when stopped and cooled down. That works very well for me.