On August 20, 2020 Under Armour implemented a so called "reCAPTCHA" on their websites which unfortunately blocks RunGap and other apps from accessing your data in an automated way.
A request for API access has been sent to Under Armour already. When API access is granted a new integration can be implemented - but this will take some days or weeks.
In the mean time you can manually download workouts in TCX format from the MapMyxxx websites and import them to RunGap.
To post workouts to MapMyxxx you can set up a Garmin Connect account and use that to indirectly send workouts to MapMyxxx. It is free to create a Garmin Connect account and you don't need a Garmin device to do so.
Thanks for your patience.
This was fixed in RunGap version 2.55 released on August 31. RunGap now uses the Under Armour Connected Fitness API to import/export workouts from/to MapMyRun/Bike/Fitness.