I was under 1/4 of a tank and filled up. After I filled up the needle has stayed on full since, but the electric display of miles to empty number still changes as I drive and works fine. Any ideas?
2021 Silverado 1500 RST

 

Well, it could be a couple of things. One, the fuel level sending unit could be stuck, or Two, the variable resistor inside the sending unit could be varnished over and not allowing contact with the resistor's wiper.

What I would try first is to add a can of Berryman B-12 Chemtool Fuel Treatment to the gas tank and see if that helps to either free the swing arm of the sending unit/clean off the varnish on the fuel level senor's variable resistor.

Good Luck!