It seems a problem is not related to the capabilities granted to a user.

1) Try to switch temporally to the default 2017 theme;
2) Try to deactivate all plugins except WooCommerce and Duplicate Posts;
3) If 2 items above will not show a source of a problem, try to reproduce it on a test data copy or if its not critical, use live data. Provide me a copy of your site files and database. I will install them at my local development environment and find a reason using PHP debug session.