FYI for those having this issue, I just got a reply to my TSI and was told this is a known issue that Apple is actively working on resolving. Hoping for a quick resolution!

Thanks for the posts here. I've been scratching my head for the past week with the same thing on a project that had been working without issue for month but now also experiencing what's outlined above: CKQuerySubscriptions fail to create with an error: "Invalid Arguments", server message = "attempting to create a subscription in a production container" fetchAllSubscriptions comes back empty even if user previously had subscriptions Manually altering a record of same type as subscription in the container dashboard temporarily restores ability to create and view subscriptions (~5 minute window mentioned above). After that period, though it just stops working again Have a ticket open with Apple but still waiting for a reply...