No way Apple (or any other company) could do that. It is impossible to test for every use-case. Also, it doesn't dictate *maximum* version/ kit requirements, only minimum.
They test that it fills the App store rules for coding (ie using public APIs/ not breaking sandboxing, not accessing things it shouldn't). But if an old app doesn't work on new kit, then it is up to the developer to fix it.
Usually if a fix doesn't fix something it means you need to delete and reinstall, so try that. The new version (2 Dec) claims to be compatible with the 6+.