New to the game (and loving it, generally); I was playing as Massalia for my first playthrough, and I was confused as to why I didn't seem to be getting any new units as my technology advanced (other than region-specific ones as I expanded). Unhappy with some of my choices, I started a new campaign as Athens and realized what the problem had been: as Massalia, I could not build any of the buildings in the mustering field/barracks tree.

I only had DEI and a couple of submods installed (none of which involved buildings), the three DEI core mods were at the bottom of the list in the mod manager, and I had conquered several different provinces and accessed iron, among other things, and still could not build them in any of my cities.

Any idea what might be wrong?