Yesterday I have been working on the twin flak M42, in an attempt to make it available as U-boat upgrade.
I have been successful, in part: the gun is displayed in the upgrades interface among other heavy AA guns, and it is fitted aboard the sub if selected.
Nonetheless, when I try walking toward it, my avatar "freezes" (I get stuck in front of it), audio changes (the bunker background sound gets replaced by a more generic ambience sound), and the screen is filled with dynamic waterdrops. I can still exit the game, give orders by way of the UI, and even navigate elsewhere using the shortcuts, but as soon I try approaching the gun again, I get stuck like before...
Seems a wrong camera setting. Maybe this explain why devs didn't include the game in game. Nonetheless, I will try and see if I can spot a mistake from my part.