I´m not sure if it is a bug, but I think it fits in here:

Playing the Romani, I conquered the provinces in Italy and Sicily. The problem is that I can hardly recruit any units there.

In Segesta I can recruit the two types of barbarian infantry, but no Roman units, although the Roman Homeland Building and Barracks were built there.

In the Greek-influenced provinces in the south (Taras, Rhegion, Messana, Syracuse) it´s basically the same thing, just without the barbarian infantry. That means, I can build only diplomats and spies.

But I´m not quite sure, if there is still some building that is needed to produce Hastati in one of the cities I mentioned above. Perhaps anyone can tell me?