This error appears when you try to run a G Merge Plus campaign but you're logged in as a user with no edit rights to the protected cells. Specifically, the spreadsheet owner has activated protection to at least one cell under the "Email Tracking Status" technical column.
Here are the recommended resolutions:
- Contact the spreadsheet owner and request that they remove protection for the cells
- Contact the spreadsheet owner and request edit rights for the protected cells
Tracking should be properly reported once any of the above steps are done.