The app showed that it was syncing via bluetooth with my device. Upon completion my device was empty of all rides and the new activity did not appear in my garmin activities. This has worked before. I'm never using this app again, or garmin connect for that matter. This needs to be fixed for others, as losing an entire ride (or more) is incredibly frustrating.
If you let us know what your device is then someone will be able to assist. I have read, but now can't find the thread, that there is a setting that can be changed to NOT delete any newly upload activities from the device.
As I said - let us know what your device is and then we can take it from there.