Lizzy here, from Shopify support.
I understand you've spoken with our team a few times so far on this, but wanted to share a few quick suggestions that might help out!
As you mentioned, accounts take take up to 48 hours to fully sync over. However, sometimes if this is the first time this store is connecting to Facebook, it can take a bit long due to the initial review. It sounds as though you may have disconnected and reconnected your account a few times. If so, this would have restarted the sync from scratch each time, making the waiting period seem much longer.
That being said, sometimes your products might have been flagged during the review process. If that's the case they'll appear here:
There will be a reason why to the right, which you can use to update the product as needed!
You'll also want to make sure that any products you want on Facebook are set to be available on the channel. You can check this in the products section of your admin!
Are you hoping to focus on Facebook as the main driver of traffic to your store?