The pictures showing are with the white panel in the wet bay in the landfill. Getting to the sensor and other things behind the old panel was impossible.
The pictures shown are not current as many changes have been made since these were taken.
You may have two sets of tank level meters. One right on the wet bay wall and one in the rv. If both are comparing you could have bad wire/connector behind the panel.
Here is my suggestion because you will need to get to the stuff there more frequently than you would really like.
My hose reel (2008 Endeavor), had the hose coming down from the bottom of the reel. The hose was a real pain to extend. With the hose reel turned 180 degrees it now drops straight down and with a new switch setup to reverse the power to the reel it now powers in and out. Had to replace the hose at one time so another reason to make access easier.
Now for the black tank sensor. The tank rinse nozzle is probably on the far end of the tank. Another modification to make your life easier.
go to the opposite side of the rv and you will likely find what should be another door but it is screwed shut. It has a hinge but is screwed shut. Remove the screws carefully so you do not mar the paint along the edges. Once you get it open install a couple of very strong magnets with epoxy or your favorite glue. And then add a simple latch along the bottom out of sight.
Looking into the newly found storage and access area you should find the black tank sprayer. Probably plugged in any case. Remove it and clean and open the tiny holes a bit. Or better yet, move it to the wet bay area on top of the tank so it actually cleans the inside of the tank near the sensors.
I had two sprayers at one time but gave up and installed a nice deck plate in the newly found space and placed the old sprayer in the landfill.
The new deck plate is clear and allows a quick glance at the actual level of the tank. And you can take the plate off and pressure wash the inside of the tank or clean with any tools you find useful.
The gray tank does not have any sprayers and I recently installed a deck plate there as well. We full time so I expected a bit of a build up there but it was cleaner than I thought. I do not use any tank chemicals. Just do not need them when dumping so often.
Once you get that stubborn wet bay panel off you can access a lot of things shown in the pictures. The water pump relay for example, or the snap disc for the bay heater.
My macerator was mounted on the floor and covered in a box. Nice for sound reduction and all but was a real pain to service. It is now a portable macerator and is stored in that nice extra space I found on the other side.
The panel shown has been recovered because the material shown just refused to stay glued properly.
The panel is simple aluminum. Making my own panel allowed me to make many changes easily. And getting it off with just four simple bolts is easy.