Welcome! We are glad to have you here! Thank you for posting into our forums!
I’m sorry to hear that your crystals are missing from you in-game account, we surely don’t want this to happen.
Unfortunately, this is an ongoing issue that is affecting several of our players, community managers have fortunately address the issue on a previous post and let the community now that developers are working hard to find a solution.
You can also check this other official post:
We very much appreciate your patience while they are looking for a fix!