Turns out I changed one of my Collection group queries recently and needed to update the index. So if you have Cloud Firestore queries that are acting erratic like mine was, check out your logcat or console log for an error like this:
Unhandled Exception: [cloud_firestore/failed-precondition] Operation was rejected because the system is not in a state required for the operation's execution. If performing a query, ensure it has been indexed via the Firebase console.
Firestore is supposed to provide a URL to build the appropriate index, but in my case the URL did not appear so I had to add it manually.
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