Adding a transaction for a in-app purchase gives a "Missing Product Id" popup

Hi, I have followed all instructions in https://developer.apple.com/documentation/storekit/in-app_purchase/original_api_for_in-app_purchase/testing_in-app_purchases_in_xcode.

My app is not on the Apple Store but is ready to submit. I have created an in-app purchase in applestoreconnect that is also ready to submit. When I try to add a transaction in the Transaction Manager, I get "Missing Product Id" with no further info about the problem. I can't seem to get any information about this online. What could be the problem?

Any idea of something I might be able to do regarding this? I have done it again from scratch to get the same error. Any way to find xcode logs that may have more information?

Adding a transaction for a in-app purchase gives a "Missing Product Id" popup
 
 
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