I recently bought two character slots none my original 7 are 50 yet (had this game dumped on me still learning) an wanna know why they are not on the choosing screen what am I missing!
I'm answering with long delay..
Character coupon is added first into your inventory. You have to click on it to activate it.
It should look like this:
Some shop items are not located in your main inventory, but in the "Pearl" inventory (2nd tab, you should pres [R1] or [R2]).