I've created a new thread in the "Technical Support" section about this issue.
I'm copying the saved file here:

Thanks!

Bug Report
Game Version: Beta 1.08.1706 (The same problem was noticed on versions: 1.08.1676, 1.07.1544, 1.07.1567.6, 1.07.1527)

Subject:
The flight altitude of drones does not change.

Description:
In my scenario, the Shahed-136 won't let me change its altitude, even though the database says ...

In my scenario, the Shahed-136 won't let me change its altitude, even though the database says "Weapon Altitude Control Possible."
I tested this on other drones with "Weapon Altitude Control Possible," and the result is the same.
The "Throttle and altitude settings" window has altitude settings ...