Maybe I found what was the problem.
I had action points spent on an enhancement that required that feat.
A window popped telling me my enhancements will be resetted, I clicked OK and it reseted enhancements and swapped feat.

Resetting enhancements costs 30 astral shards. But it did not specify it would have used astral shards to reset them, otherwise I would have closed the process and resetted them manually with plats.

How could I have known? I even expected it to be a free reset, not even costing plats.