A variant?

Fought a succesful seige, mighty Carthage taking Osca from the Scipi. Full stack including 2 units of hefalumps no losses both still 12 each. After battle redistributing units between stacks and moved hefers & a general to a neighbouring stack. After the exchange screen I reviewed the two stacks and 2 hefs AND general had disapeared! Not in either stack or anywhere nearby.