When you try to pickup turned off turrets with a hammer, it says "turret has attachment" even if completely unloaded. I think it's due to the switch attached.

Yeah it's because of the switch. A Rust update changed the behavior so IO Entities can no longer be picked up if they have a child entity. This was reported in another thread and is affecting multiple of my plugins. I have partially implemented a fix, I just need to do some more testing and should have it out soon. This is one of my highest priorities.