This bug is also on BD. Its worth pointing out you get the correct amount of crystals each and that its just an events bug.
I believe this bug occurs because of the order of things that happen when you take an outposts. You take control of the outpost and then the sharing of crystals occurs. As you own the outpost when the sharing of crystals happens it informs you that you have lost crystals to yourself and whatever allies have attacked with you.