Yes your inventory is full, you have maximum number of equipment in inventory, so there are 2 ways, either you break some of them (from normal inventory) into peaces or you just discard some coffer (but you don't have any coffer only equipment, so you can only break equipment into peaces) only after youdothat you will have 1 free spot and you can put your equipment from temporary inventory into regular.

I think this is the UI resolution issue that some of our players are experiencing since the last update. As a temporary workaround, use full screen mode when facing problems like this - it should help you access the interface buttons that you need. In the meanwhile, please post your screen resolution values here. We are currently working out a pattern to investigate the issue more efficiently.