But it's clearly a bug, although a low priority one of course, because it's healing itself.
You didn't do the right steps to reproduce, so clearly you couldn't reproduce. It seems to be very likely, it's needed to hover the capacities, after Main Hall is upgraded to max. level without relogging.
I'm quite sure, that Adobe is telling their customers to advise their users to do cache- and history-cleaning, so Innogames isn't to blame. But I still won't do, in the given thread is said, that you can do without.