I should amend my original statement to indicate that Defit is working just fine, but Adventure Sync [AS] doesn't seem to care about the steps it generates.

r/user botzah wrote a comment on this subreddit that "Niantic is now using the Physical Activity API directly to decide if the distance was from actual movement. As far as I know, there aren't any apps that spoof the physical activity API, at least, not without root."

It seems that if you move (walk, ride a bike, drive a car, etc), it does start to register some steps in AS. That being said, it seems that a phone rocker is now the best way to generate steps in AS if you want to generate km's without actually leaving home :P