I agree with Grumpy. When it shows full keep running cold water to the shower or sink until it starts to back up in shower. Then you will know if gauges are off.
Many past posts about cleaning materials for tanks plus people who have replaced sensors or sensor systems to get a more accurate measure.
If it is full and shows full but does not empty several posts on that. If you can, run a hose back up the drain pipe with water running and see if you can break a clog.
2017 SLX 195RB
2021 Jeep Grand Cherokee Summit L 5.7L V8
Andersen WDH hitch, Renogy 100 AH Lithium &
200 Watts solar panels from Renogy
Prev. '14 Jeep Grand Cherokee Overland, gas 3.6 V6