I had this happen once when the kids put lots of toilet paper and it was enough to block both the closet and air pipes, I accidentally freed it up by standing on the pedal and prodding the toilet paper with a stick woos and splash and it started to empty I filled and emptied it four times to clean it out, so in the end it was simple science no air in no fluids out.
"Well that didn't go as expected"
2015 Chev 2500HD Highcountry Duramax
Cedar Creek Silverback 33IK
Donald&Casey cairn terrier
Rest in Peace Mary my darling wife.
Scottish by birth Canadian by time.