Strava Live only works for flat/uphill sections.
Using Polar Flow you can only sync flat or uphill sections with the Strava Live feature. This makes the Strava Live feature on the Polar V650, for example, a completely useless feature for mountains bikers how might wish to use the bike computer for more than just pedalling uphill.
There are many, many mountain bikers use mainly use Strava for recording their times on downhill sections of trails. And not having the ability to link Strava Live to these downhill sections is a real shame.
I really hope that Strava and/or Polar put their heads together and fix this issue.