Corinium Duo 2019 Waste Water Level Sensor

Hi All
Any advice would be appreciated please. I have just noticed that my waste water level on the Control Panel is showing 25%, when the tank is empty. It appears that when the tank is 25% full, then the panel shows 50%. Any ideas where I can start please. I have powered off the complete electrical system and restarted, hoping that it was just a glitch, but fear it may be more complicated

Eternal question on here, but as a newbie you'd not Know!
Go to Search (top rhs main page), type in water sensor there's all you need, applies to most questions actually. Please don't ask re tyre pressures!!!!!!

Answers usually are in 2 ways, those who fix or think they've fixed them or, the other 50% or so, like me.

Here's my solution..

Park on level, lower waste pipe and open tap.
Does anything come out, if yes, then leave tap open till nothing comes out, the tank is EMPTY!
If no, the tank was already EMPTY

If in use the sink or handbasins won't drain, the tank is FULL, empty it!

Anything in between with any gauges is pure guess work in the majority of cases.
Mine is much more accurate than yours, btw, it doesn't have one!!

As Ian says, the malfunction of the tank gauges is indeed The Eternal Question on the Forum (along with What tyre pressures?).

Most gauges involve sensors / probes in the tanks. They get coated in lime / grease / all sorts of gunge, thus rendering the readings unreliable. In the first few years of ownership, I fussed remorselessly about the gauges. After all, they have been provided and could be most useful, so make them work properly. But after endless frustration, and against my instinct, I learned to live with their idiosyncrasies. I surrendered. I retained my relative sanity. 

On a site, I can tell when my fresh water tank is full: it overflows; I can estimate how much is left - and likewise how much has gone into the grey water tank. I empty / fill as necessary. Works for me... without losing any more hair.