I dropped a full day on the “could not get offerings” issue that a lot of other people have experienced. The main cause of this was misleading/lacking documentation in the IOS Product Setup guide here.

At the top of the document, it says: 
 

Make sure Paid Applications Agreement is signed

Before you set up your products, make sure you have the latest Paid Applications Agreement signed in in the "Agreements, Tax, and Banking" module in App Store Connect. You will not be able to test in-app purchases until the latest version of this agreement is signed with Apple.

This is partially correct, which, in many people’s cases, means that it’s incorrect. You must also 1) fill out all the tax documentation, and 2) submit a bank account and have it approved. This was not clear to me, so I spent forever tracking down the error.

Later in the guide it says:
 

If you don't see the Subscriptions option, ensure your developer account has accepted all applicable contracts and have provided tax and banking information

This is similarly misleading. I did not have tax and banking information, but the Subscription option was enabled, so this language made it seem like providing tax and banking information was optional. Please, please, please make it very clear at the top of the guide that ALL of these things MUST be done before continuing. I think it will save people a ton of time (just look for the number of forum posts where people post a problem with retrieving offerings, someone suggests they fill out the bank/tax information, and it solves the problem).

Thanks for listening!