When upgradading floating houses, pop limit is reduced

Just bought 3 floating houses for gems (right after maintenance). When I upgrade them, the pop limit is reduced untill after the upgrade. Looks like a bug to me. Also it reduced my licences temporarily to -1.

update:
ok now my pop limit is back to the old limit. So I gained nothing by adding 3 floating residences. Old pop limit 6100. New pop limit 6100 :-S

update2:
After about 5 minutes the lost pop was added. So at 6250 now. Wonder what went wrong? Lag?

It does seem to be super laggy this morning (another successful maintenance...) Me and a guild mate buffed each other and it took forever for the buffs to "stick"