This is an accepted solution.
To provide some context, when this issue comes up, it is typically because your pages' roles are not what we'd require. The "Page Roles" for the Facebook Business account are "Custom" as opposed to "Admin" (This can also present itself as the title of the custom role itself, so this is not exact for all accounts).
The purpose of a "Custom" account is that the role is limited to a selection of tasks able to be completed, and this restricts third parties (such as Shopify) from full access to the Facebook page, for things like the Facebook Sales Channel and Instagram Sales Channel. This does not allow the channels to work as expected.
To resolve this issue, you'll need to review your page roles within your personal Facebook account via the Facebook Page - > Settings -> Pages Roles:
We do not want to see "Custom" (or the title of the custom role) in this section. If this is what you do see, then you'll need to disable the options below in your Facebook Business Manager account.
1. Click business Settings:
2. Select the page:
3. Disable the two options as seen below
If we disable these options, you will be recognized as a standard page "Admin," and we can then connect to the Facebook Sales Channel as expected. Once the "Manage Jobs" and "View Earnings Insights" settings above are disabled, we should see the desired settings on the right:
Once done, you should then be able to connect your Facebook page to the Facebook sales channel. Once you have, your store will go into the review process, which can take between 48-72 hours.
Let me know how that turns out!