Might be a ECU issue. You might try disconnecting the battery and leave it off for a minute, then replace it. that will erase the adaption i believe a reset certain things like the fuel gauge. It may show no fuel after you do that but will gradually come back. Go fill up and after a few miles it should show correctly and hopefully will be correct. if not you can try reloading the tune if you have tuneecu. But if it is a ecu issue i bet the battery disconnect will fix it. I've had similar issues that straightened themselves out when you give the ECU a slap in the face one of several ways.