Ok, first thing to check is make sure Arc definitely has Health permissions, in your phone’s Settings → Privacy → Health. Arc needs at least “Workouts” and “Workout Routes” to be able to import.
Second thing is … just to wait a minute. Arc checks to see if there’s workouts at most once every 5 minutes. So if the workout is new, Arc should see it within 5 minutes.
Yep! That’s Arc’s “sleep mode”. When your stationary Arc’s recording engine goes to sleep, to conserve battery. While in sleep mode it does brief wakeup checks every 12-60 seconds, to see if you’ve moved. Then if you really are moving again, Arc will go into full recording mode, and you’ll see the current location dot on the map.