Update, October 20: App Review reviewed the app this afternoon. The only issue was guideline 1.4.1: our App Store description needed a disclaimer reminding users to seek a doctor's advice. We added it within the hour and, at App Review's request, resubmitted the same build (version 1.0.2, build 130). It's back in Waiting for Review, so if App Review can take another look soon, we'd be very grateful. @ExpressiveSolutionsDeveloper our 3.1.1 rejection was different: the app had a field where people could enter an access code to unlock the subscription, and only In-App Purchase may unlock paid features, so we removed that field entirely. Good luck with yours.