Buy six items and sell an item, now you cant buy anymore

unless you re-arrange your inventory.

I can confirm this, you cannot buy after you sell an item when your inventory is full until you either sell an item or rearrange your items.

I know I had seen another thread on this awhile back, and I've just experienced this as well while playing as Teemo. After selling my Kage's, the only things I could buy were consumables, which actually went into my inventory instead of being consumed like when your inventory is usually filled.