Why can't I sell/undo things in my shop

Hello can someone help me..

A friend of mine has some kind of bug in his account. At the start of the game he buys his starting items but once he needs to sell the item he can't. This has nothing to do with the resolution or something he just cant sell it, even not with right clicks on the item. We already reported a bug but nothing. And since this is pretty annoying for the game experience I ask here for help. Hopefully someone knows what else we can do. We already deleted League and downloaded it again. Nothing helps....

( He has this on every computer, so it's really in his account. )

And before someone ask if he's on the base, yes he's on the base for sure he just can't sell..