Could be the temp!
Has anyone had a revival of the yeast by just "gently" rousing the yeast by moving their fermentor/carboy?
Once, I had to move one of my fermentors late in the ferment, their was no visible activity for 2 days but after moving the carboy I started getting CO2 for about a day. I know I was close to FG but I still got some CO2. Temperature stayed the same!
I have no knowledge here, just what I observed.