Let's determine what's causing the Mileage tab to disappear, delabinc.

I've checked on my end for any outstanding investigation about this one. To determine what's causing the issue, let's open QuickBooks on a private window. You can use these keyboard shortcuts to open one:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Shift + N

If it works, we can go back to a regular browser and clear its cache. A piled cache also be the reason for some unexpected issues on the pages we've opened.

We can also switch to a different browser like Google Chrome, Mozilla Firefox, Microsoft Edge, or Safari.

Afterward, let's check to see if the Mileage tab now appears on the left panel. You can also check this article for more information about Mileage:Manually track mileage for multiple vehicles.

I'm just here to help if you have other concerns about the multi-user network. Stay safe!