Yes, with all my Commanders the fuel sensors and gauging has always been bad. What I did in the 520 is drained it and calibrated the gauge - it was empty when it still showed 50 gals or something! Also never showed full properly, just stayed below there for a really long time until the levels dropped. Unless you're willing to exchange the sensors for newer solid state ones and get a 337, they're just going to stay iffy.
In the turbine it's the same thing. Meters get stuck, not showing right amount etc - it's all over the shop. Thankfully there the Foxboro fuel totalizer is very accurate, so as long as you know how much you have in tanks initially, you can plan very accurately.