In my opinion, the reason for the lack of movement of the tower lies in the conf.ini file - section [game] - viewSet =?
I had viewSet=37 set. With this value, when I enter the gunner's position, I have control over the weapons right away - I can aim and shoot. Using the 'Autopilot enable / disable' function causes the AI to take control of the turret armament and I become just an observer. Unfortunately - in the external view of the Ju-288, the armament, when I move it, remains in the neutral position all the time. However, in other planes it moves correctly.
When I set viewSet=81 - entering the gunner's position - it is under AI control and I can only observe his actions from inside the tower. Only when the 'Autopilot Enable / Disable' function is used - I take control of the turret armament. In this viewSet setting, the tower in the external view moves correctly all the time. Even when I control it.
I hope that I have described the topic clearly.
Personally, I definitely prefer the first option - viewSet=37. I think that the behavior of the tower in the external view with this setting can be somehow improved in the class file (since it works correctly in other planes - e.g. B-29). However, this is not a problem - more of a curiosity and a topic for better understanding the secrets of the game.
A question for others - how do you set your viewSet=?