I had an issue where my shopify products were not showing in Facebook. Despite deleting the FB connection and reconnecting my FB page 3 times from Shopiy it still didn't work. However based on another post here, here's what worked:
1) Logging out of Facebook in my Chrome browser.
2) Open new browser page Incognito then logging back into Facebook.
My products appeared!!!
This seems to support caching problems.
Clearing the cache did not work for me, neither did incognito, I was getting a constant re-direct. as follows
Turning OFF blocking 3rd party cookies fixed the problem in chrome browser "Settings".. advanced security.
My store is now connected to facebook and the page linked.
I suggest you first fill in all relevent page details in SETTINGS in your public page (not your personal facebook page).
I chose the shopping template as suggested earlier in this thread.
I'm having the same issue...shopify advised I wasn't the account holder...lol...nonsense, I created the page, I'm the admin, owner & business manager and nothing has been done by anyone....long time wasting exercise and I need assistance, keep getting bounced fromFB support to Shopify.....Devs clearly haven't got a clue let alone shopify support.
Did you enable 3rd party cookies? try via incognito? clear your cache? I had to choose the shop template, create an @Name, make the page visible of course, and I also put in my credit details for my business manager account and set up an ad account. But primarily I think unblocking 3rd party cookies did it for me. In the incognito chrome browser.