Ah, that could be it. I only have the first Nav tech researched, I'll try the next one. Thanks.
On that note, what's the difference between the Nav Bombers in this game? There are two options in the build queue, one of them has the country's specific name for the bomber, and another one is just "Basic Nav Bomber". They have different stats and costs, too. One of them is good at Sea Attack and the other isn't but has longer range or something. It also has a different picture in the icon. Is this an intentional addition within the mod, I assume? If so, what's the point of building the one with the lower Sea Attack stats?
Edit: Italy comes with the first Nav tech, the 1938 one, researched. The next one is a 1941. So, I'm really hoping that's not it. There's no way a 1941 tech can be a pre-req to a 1936 tech...