I also have the same problem on my digital gauge, tank level remains unchanged (but still reads). I was told the sender was the issue, as mentioned. I am unable to remove the sender from my tank, one of the thru-bolt heads is stripped. Can't drill it out at risk of debris entering the fuel mix, so I'm stuck with it.
With the Yamaha Fuel Management System, I simply track the number of gallons burned (knowing I have a 93 gal. tank) after fill-up.
Try this if no luck with the sender.