Nick here from Shopify.
That does seem very strange for sure. Something to double-check in your Facebook settings is to make sure you have an admin role as in the Shopify help guide it states you must have an admin role for a Page, Ad account, or Business Manager before you can access all of its settings and make certain kinds of changes to it. Pages, Ad accounts, and Business Managers have separate account permissions, which means that you need admin roles for each one. Can you confirm you are the admin of these aspects of the Facebook page?
These admin settings are based in Facebook and you can only adjust them there. You can find out more about these roles in Facebook's help board here.
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