I first noticed it around 0.8, but for some reason it seems like the only vehicle-mounted turrets I can get working are Flamethrowers. Plasma Guns will fire and consume ammo but do no damage, Machine Guns I can’t seem to load (They won’t except ammo from bins inside the vehicle, and ammo dropped on the turrets just falls through.) Fusion Guns I never figured out how to properly load sad to say.
Flamethrowers are wonderful, but they also have a horrible tendency to destroy my vehicle.
Some energy weapons may be bugged in general, there was an issue with the laser finger thingy, not sure if it also affected turrets, have you tried the mounted machine gun?
I did but I couldn’t figure out how to load it, in an earlier version (0.6 I think?) you just dumped ammo on it and it used it but that causes it to fall though now. As far as the plasma weapon is concerned it fires (There’s a message) and it uses ammo, but it doesn’t emit a projectile.