Sure.
First off, there’s no official mobile app. There are a couple of apps developed by other users and doing a great job of displaying data coming from the Intervals API.
Your specific issue:
the iPad app has its form calculation setting set to %. -44% is the result of an absolute form number of 15 relative to the Fitness number.
The web Intervals has its form setting to absolute value and is 34-49=-15 (NOT percentage but absolute number)