The really odd thing about it is you being able to build a fire node over it. This would normally indicate that the mana had changed cultural borders and thus wasn't actually mana (hence you not having it). But if after building that fire node you didn't even get the fire, and it was properly connected, then all bets are a bit off.
When you get it back, and rebuild it as your chaos node, if it still doesn't give you mana, please also let us know if you are still able to select a new node to build on it.