Thank you for sharing this experience with us, Jessica.
Since this is a behavior on the inputted data, I would recommend getting in touch with our QBO Support team. This way, they can gather more details and investigate why the mileage records that are marked as favorites can't be added to trips.
- Click on Help and click the Search tab.
- Click Contact Us at the bottom.
- Enter something like mileage issue and click Continue.
- Choose Start a chat or Get a callback.
On the other hand, you can check out more references in QBO on the main support page. Just click More topics to see more of them.
Let me know if you have any other questions in mind.