I've submitted a ticket because I am disappointed in the response here.
Fixing a bug is fine. Bugs happen, if it was not intended, oh well. But changing the mechanics of the kit is not cool. It is pure bait and switch. They added an ability, people spent resources on that ability (those resources may have cost real money). Then they change it because thet realized they designed it poorly. So they need to refund it if people want to buy it again, they can.
Changing the kit like this always triggered a refund of the materials (in fact they refunded much more subtitle changes than this).