Adding storage to Android TV Television

I have a buddy of mine who has a 65 in Phillips android tv. He bought a thumb drive and it will let him format as device storage. But after a few minutes it resorts back to removable storage. What could be the cause. Its a sandisk 32gb thumb drive

It could be android blocking it. Check all permissions in settings

It doesnt really matter. It will still be usable as additional storage for the tv.