@m_adam I've run into the copy/paste UserData bug a few times. Glad it's been reported!

Hi, The Test tag plugin is missing in the linked c4d file but I see the behavior with another tag plugin (Py-LookAtCamera SDK example). I was wrong in my previous post. This behavior of the Attribute Manager is applied to tags that can be added only once to an object. This can't be done for tags that can be added multiple times. Unfortunately the Python tag is registered with TAG_MULTIPLE flag so it can be added multiple times to an object but the parameter tab isn't attached to its parent object.

Thanks dskeith, that code worked perfectly. Thanks for that!