spot data feed subscription not working

I followed info at https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-data-feeds.html to subscribe to the spot data feed after verifying with a dry-run as described at https://docs.aws.amazon.com/cli/latest/reference/ec2/create-spot-datafeed-subscription.html. However, I'm not seeing any new data in my bucket.

What I want to verify is that if I stop and then restart my persistent spot instance then that instance is still getting the spot pricing rather than switching over to on-demand pricing. I'd also like to get a sense of the price variability.