Thank you for sharing your concern here on the Community page. Let's figure out the possible reasons why mileage transactions aren't showing up on your account.
Since your application is already tracking your mileage data, you can update your device to get your records (steps may vary depending on your device). On the other hand, you can reload your mileage data if you're using a web browser.
Open your QuickBooks Online (QBO) account, then click on Mileage at the left pane.
Switch your options from the Unreviewed, All, Business, and Personal columns.
Tap on the reload tab to refresh the page and bring your mileage transactions.