I had all the same issues all of you had and solved it. Me and another user had 'Admin' privileges in the business manager, yet Shopify said I did not. Here is what worked.
reply if this worked for you.
Cannot thank you enough. Spent several hours going through old forums and contacting Shopify to no avail.
To anyone reading this, the solution for me was: "Click on the ARROW to the far right of your name and make sure that MANAGE JOBS and VIEW EARNINGS INSIGHTS is turned OFF and that MANAGE PAGE is ON (this means you will have admin privs here too)--> select SAVE"
No idea why this would affect anything but it did. Thank you again.
I confirm - the only way to solve this problem is to navigate to FB business manager, make sure you're an Admin, then turn off the manage jobs, and view earnings , on top of that I would add, you should use Chrome as a browser. For whatever reason this would not work when I was using safari. Such a strange and very particular bug!