This trick works!! thanks !!!! Really full of bug on shopify with FB catalog
I got the same problem and was struggling for hours.
Step 1: What I did is creating a new campaign, choose conversion, sell from catalog.
Step 2: Next step choose below the Shopify catalog with your products and go to the next page, now Facebook is asking you to connect this catalog to a Facebook pixel. Choose your pixel and Facebook connected it with the Shopify catalog :)
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