2015 XLR having "issues" with back bathroom toilet. When it is flushed it acts like the bowl water is under pressure (creates a small gyser ), never empties and just keeps filling the bowl. I have plungered (new word.
for today) it, with the water on and off; the black water tank is empty; I have snaked it. Still no change. The forward toilet works fine and doesn't seem to be backing up into the back toilet, sink, shower, everything else works. Any suggestions what the problem is and how to fix it???