For example, with Notepad++ you can right click a file and you see an "Edit with Notepad++" item. Because these context menus items are added via registry (and the MSIX container-izes it), the OS is unaware of the new context menu item.
You can add context menu with MSIX, but you can do this only with File Type Associations (like in VLC for example) that point to an executable (you can call this a shell menu).
Context menus are not added via the registry in MSIX, these must be added in the AppManifest.xml.
You can read more about this here:
