Hello
I managed (unfortunately) to find a very nasty bug.
It can be see as a combination of multiple “issues”.
I had a full inventory, i sell an item, then convert a green item to a crystal. At the time i click on the convert button i have a free slot (and i was thinking a would have another free slot).
I have all but the amethyst crystal, and all my crystal are “checked” (i mean i clicked on each one so none of them is showing that a new item is added).
After spending money, an item was picked and added to my inventory, and so, i only have one free slot (the green item converted).
I check my crystals, and… no new crystal was added !
I presume the rng granted me a new amethyst but i presume the order of actions was not as expected :
after converting the green item, a new item was picked, no slot avaliable so amethyst was trashed, and only then the green item was removed. (i was presuming the converted item is removed and only then the crystal is added).
Sad enough i’m not so often lucky to have such high grade crystal.
After a while i converted another blue item (and checked to have at least 3 slots) and get another amethyst (i will keep it to prevent me from having this bug again 
) .
I hope you will correct this annoying bug.
Happy new year 2016. 