Hello Bas,
I have never had Start10. I had the Start11 v1.0 on Windows 10 before, updated to Windows 11 preview, reverted to Windows 10 and uninstalled Start 11.
Giving it another try now, I installed Start11 v1.1 on Windows 10 and noticed that not all app groups were imported from the Windows 10 Start menu to the Start 11 Start menu. After, I updated to Windows 11, so that is not of influence in the case.
Below a screenshot of the Windows 10 Start menu as it used to be for your reference. It were the Start Groups top left and bottom right which were not imported. These and other groups contain Edge (Chromium) app installs.

Cheers,
Joscelin