Fresh water tank won't completely fill

[lwg]

We seem to consistently have a problem where we can't fully fill our fresh water tank. I usually can only get the tank to show 1/3 full before the overflow tube well, overflows. Prior to our last move over time it slowly starting filling up more and more. I think this might have been due to me "resetting" the coach with the level-up system and possibly removing an air bubble? This is my best guess so far.

We know it's not full as we can currently barely get two loads of water out of it and maybe a shower. Best estimate is that this should be no more than about 25 gallons of water.

Thoughts?