The problem is this: to add a custom label to a tag, the tag needs to be a shared parameter. When the room tag is loaded into the project, the label that corresponds to that parameter (for example, a text shared parameter called "Room Dimensions"), remains uneditable because that parameter does not exist yet in the project. That's why you can't edit the ? symbol.
Solution: Manage > Project parameters > Add > Shared parameter > Select > (find your "Room Dimensions" parameter or similar) > Instance > applies to from the list of categories on the right, select "Rooms" > OK.
Now, click on the tag, hover the mouse over the ? symbol, and now you should see a tooltip that says "Edit parameter", just click on ? symbol, and you will be able to type in it. Also, if you click on the room entity, now the parameter will be available also in the properties of the room. None of these things were happening before because the parameter had not been added to this project. It works in the other project because the parameter was added to that project, not to this one.
Alfredo Medina _________________________________________________________________ ______
Licensed Architect (Florida) | Freelance Instructor | Profile on Linkedin