Hi Mr G1 Thanks for reaching out to us here on the Community. We'd be grateful if you can refer to and follow the steps in the article provided to establish if they resolve the issue that you're experiencing. Please reach out to us if the steps don't resolve the issue and you require further assistance. 
IOS device: https://quickbooks.intuit.com/learn-support/en-uk/help-article/track-mileage/fix-mileage-tracking-is...

Android: https://quickbooks.intuit.com/learn-support/en-uk/help-article/mobile-apps/fix-mileage-tracking-issu...