Verify that your iOS privacy settings allow access to Apple Health step data

1) Go to your iOS Settings & select 'Privacy'
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2) Select 'Health' app
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3) Select the name of your Challenge App
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4) Allow your Challenge App to read 'Health' Steps
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You can find more information about tracking activities with Apple Health and your Apple iPhone and Watch here:

https://support.apple.com/en-us/HT204351