Cache buildings

I made a kind of engine that stores every unit/building on a map to the game cache including its current life, mana, rotation, owner, x-position, y-position blablabla.

You can then enter for example a house, and when you get back to the first map everything will be like it had been before because all the units are loaded again from the cache.

ONE PROBLEM:

Buildings have a really strang behaviour, they seem to be repaired or something, but have the original life and can even train units as usual (but they show the repairing animation for some time)

Can this be caused by the place where they are placed?

anyone with the same problem???