New Starting Point: Armenians to Osca

Folks, I tried an experiment. I think I did something wrong.

My intention was to just transplant Spain and Armenian armies, and play as Armenia in Iberia.

Here's what I did.

Edited descr campaign file:

1) Moved and interchanged all General, Spy, and Diplomat units for the respective Spain and Armenian Armies.

2) Cut/Pasted Spain's old towns to Armenia, and vice versa.

3) Changed "Builder" of cities for the New Armenian towns to Parthia.

4) Changed "Builder" of cities for New Spain towns to Gaul.

I am able to play just fine, however I encounter one very very strange bug:

The bug: Osca will *not* grow over 4400 people. I can't get it to work. I even tried moving about 17 peasant units into Osca, and disbanded them, hoping to get a city-growth triggered, but it didn't happen, and city growth rate changed to negative 4.5%. Even letting a turn lapse, with population of Osca still over 6k, I did *not* get a city growth trigger.

Has anyone seen anything like this?