TrainAsONE requires that your workouts have deep analytics of the laps, GPS, or distance. Generally when you are not seeing data in TrainAsONE it is because the data is not sufficiently rich for TrainAsONE to make use of it.
If you are not sure if you do or do not have data with deep analytics, the easiest way to tell is to look at your Stream and see if there is a Download link for GPX or TCX files. If you do not have data with deep analytics, make sure that FitnessSyncer is configured to use it. For example, this information would only come through for Garmin Connect (Sports) and would not be available in Garmin Connect (Wellness).