Help! Cannot build some units at all

[mihai1403]

I think this is a bug. I didn't report this at first because I wanted to make sure there wasn't some missing requirements but there are 2 units you start with that I simply cannot build.

Scenario: On the brink of toimorrow
Nation: Romania

Units I cannot build: Artillery and Corvette or their alter iterations e.g. Destroyer

Not sure why this is. Initially I thought maybe I needed a project or some other sort of requirement like upgraded building, but no. It's now year 2052 and still no such units as a build option. I got military shipyards and bases. I can build carriers, gunships etc, but not the above units.

Any idea?