No matter what I do, an item stays in the inventory.

When I try to add a clothing item I know I have in my wardrobe, I'm not getting an error and ofcourse it stays in my inventory. But when I try to to add it in my Vault, it won't go. No item I try to add to the Vault, goes to the Vault. Everything stays in my inventory.

I used Firefox while encountering this problem.

It's on Kumos.

I encounter the same problem on my Endroid phone while using Firefox.