Steps to repro:
- create a uxml document with a bunch of controls ( or use the one attached file )
- create a ui document in the unity hierarchy ( Create -> UI Toolkit -> UI Document )
- Set the document to use the uxml document you created
- Add a secondary game view ( ellipsis next to inspector -> add tab -> game )
- You should now see your UI on both screen
- Hit the resolution drop down ( free aspect ) going back and forth between both game view
Result:
You'll see that there's a rescale issue happening and even the background is sometimes not showing up.