It's very very unlikely it's physically stuck unless you recently did work remove n replace however it's common for the potentiometer wiper to get weak enough it doesn't properly register.
If you look at test six you can determine if it's left or right side.
I have a DIY repair for the issue:
https://xoutpost.com/bmw-sav-forums/...uel-gauge.html
You can use test 21 to reset the OBC including fuel gauge averaging but that thread it shows how to figure out which side is failing and how to repair the float resistance issue which should be your problem and fix.
Watch your test six while driving and whichever side will suddenly change and not from sloshing that's the culprit.
When mine was malfunctioning, I would fill complete tank and it would only read 2/3. I would often only fill 1/2-2/3 so I probably went months in that scenario before i went on a road trip and did complete fills and noticed right away it only showed 2/3 tank leaving the bgaa station but would slowly climb as i drove.