Create a new blank Maya scene for the rig file before referencing in the model.
Start the rig in a clean, empty scene. This keeps the rig file separate from the model file and avoids carrying unwanted objects, history, or setup data into the rigging scene.
Begin from a blank Maya scene before setting up the rig file.
After the clean scene is created, reference in the prepared model file and continue with the fitting and build workflow.
Keep model preparation and rig building in separate files: model edits in the model file, rigging edits in the rig file.