Can anybody tell me where the challenges are in the new app?
There are some know issues with the Vivofit 2 and new connect app, they will be fixed ASAP.
iOS https://forums.garmin.com/showthread.php?329214-Garmin-Connect-Mobile-3-0-Known-Issues-Updated-10-22-2015
Android https://forums.garmin.com/showthread.php?329213-Garmin-Connect-Mobile-3-0-Android-Known-Issues-Updated-10-22-2015
And check post #24 in this thread https://forums.garmin.com/showthread.php?329498-Activities-not-syncing-with-Garmin-Connect-on-Vivofit-2/page3