Glitches and exploits in Heroes.

I've encountered this bug several times (it's not exactly helpful, quite the opposite): when a secondary hero is in my castle and is attacked by the AI, they can defend themselves if they have a decent army. However, if they successfully defend, they receive a large amount of experience, but when I click on the castle to build something, it turns out that the castle is empty, and my victorious hero is in the tavern with all their experience and no army. This has happened several times. It's very inconvenient. It's even frustrating, to be honest.