Yes. Currently, App Center doesn't support iOS 7. The most recent version on AppCenterLabs (4.1.13) will gracefully close, with a message stating that iOS 7 isn't yet supported. There should be a release before on on the release date of iOS 7 (likely mid-late September) that will add base support for iOS 7. I would not expect that version to support all the new MDM features that iOS 7 adds, but should allow all iOS 6 types functions to work in iOS 7.