shinypenny says:

Due to the bug:

www.runnerplus.com/forum/topicpage-9-307-challenges_development-0#2700

 kgriffon says:

Hmm, I plan on running and walking on different workouts. Should I abstain from the walking group? Otherwise my run data would be included there too, wouldn't it?

 shinypenny says:

If it were me, I would probably stay in the walking challenge for now - if the bug gets fixed before the end of the challenge and the pace limit is reinstated, the challenge will automatically update itself with your qualifying mileage. Up to you.