Hey there,
I've completed the 5 walking activities requirement, but the badge isn't earned. Is there something I'm missing?
Thanks!
I don't see the date requirement on the badge description though.
Look at it on Garmin Connect Web - the availability is at the bottom. Just, as I wrote, the effective availability of latest batch of the new badges was for some reason delayed by two days, so instead of April 28, it is rather the 30th April

is there a reason my activities would not be registering for the badges?
Yes, the Walk the Walks badges 2-5 were introduced yesterday, so you may need to edit and save all non-counted Walk activitites between April 28 (the start of their validity) and yesterday to have them counted.