It's not that... well, sort of it is. When you finish the council quest, it disappears from your inventory, and you have to manually refresh your inventory to see it again. Then there's also the issue that if you use a familiar, generally the mosquito or maybe black cat if running bad moon being generally the only other time you won't have a terrarium, without remembering to use the terrarium first... it considers the familiar item to be used, even though the addition to the terrarium failed. Have to either manually refresh, or go through the browser to add them after that.