In my case, the barbarian settlement doesn't upgrade with more than 12000 people. When the settlement is upgraded to city, there is no indication about the next population level for the following upgrade.

But (and this is even stranger) when I put the settlement in descr_strat as large_city with 12500 and proconsuls_palace in it, the building appears in the campaign map, the new settlement (greek-roman one) is ok, but again there is no indication about the population level necessary for the huge_city level, which is also defined in export_descr_buildings, export_descr_buildings_enum, export_buildings and with card in Data\ui\barbarian\buildings. The settlements are defined in descr_sm_settlements.

Any idea about this problem?