This issue should be resolved with patch 0.3.2. If you continue to experience this issue, please reach out to us through our support site to let us know.
When trying to put items into their last available slot in the inventory, some players are finding they are unable to do so.
PC, Xbox One
There is an issue where storage containers are full but are not showing all of the items in the container. Removing everything from the container, or destroying the container, will allow the player to retrieve all of the items.