I've just gone through the configuration in case I've missed something, but it looks like this could be a bug. Turrets are enabled, but they're not showing at all.
Thanks.
I see this no longer has a maintainer. Hopefully someone will pick this up soon as it's a massively used plugin.
Anyway. Further information on the turrets issue. It seems like the flamethrower turrets are showing, but not the regular ones.