You may get more responses if you post this in the Workgroup PDM section. For what it is worth, we don't have the problems you are seeing. I've attached a couple of screen shots showing what I think are the relevant options.
Welcome to the forum. I don't use PDM so I won't be any help there, but the policy here where I work concerning library parts is to copy the library parts to the folder for the current project. Then use those parts in the assembly. That way they can be modified without affecting the library parts, and they aren't tied up so other people can't use them.