Thank you for reaching out to the community forums for help with your Facebook sales channel. I understand that your business page is owned by a business manager different from the one you connected to originally. This can feel a bit tricky to get resolved, but we have some amazing resources to help you out.
Our community support has a full breakdown of the most common issues with onboarding the Facebook sales channel and you can find them here: Facebook Channel Troubleshooting. I would go through the steps for both the business manager and business page permissions to ensure that you know what account is managing what information. Please feel free to also contact our live support for additional help in this process!
To contact our live support please follow this link: Shopify Help Center - Contact Support, sign into your store account, search for your issue and use the contact support button at the bottom of the search results to see all our live support options.