steps sync - automatically removing steps from running activities?

I'm syncing some Garmin metrics to TrainingPeaks, generally no issues. 

However, I'm noticing that the number of steps that get synced to TrainingPeaks on days I have running activities *do not* match the number of steps on the watch or on Garmin Connect. 

This is -only- on days when I have running workouts. I surmise that the sync is somehow subtracting steps from the workout, but I don't see this documented anywhere. 

Can someone Garmin confirm this is what's going on?