It appears to be really random as to when they bug, which is really worse. Some people are reporting bugs with items that went perfectly fine for me. You're just really taking chances I think when using unlocks of any kind.
It honestly wouldn't be an issue if they provided support to fix the problem. That's the real problem actually. The fact that there are bugs is normal, which game doesn't have bugs? But if they won't fix the problem afterwards, then it's a very, very serious issue.