Today I spent 6 hours (!) trying to figure out this error:
"Invalid IPA: The keychain-access-group in the embedded.mobileprovision and your binary don't match."
I finally discovered the problem after following the steps described on this document on "How to create an IPA". For some reason, my "Archive" scheme settings were changed and had the Build Configuration set to "Release" instead of "Ad Hoc", as it should...
Thank you, TestFlightApp support.