Comment 65 for bug 1946368

Daniel: You have to activate the developer options inside the update management. Only then, you get the update from propose canal! A normal update does not help without a development option. This option you get when click settings in Main window of update management ( Software & Updates program ).
After switch on development option new package are reading into your system. After ending this download you can click ok from update management to start a search for new updates inside propose canal. This update is a pre-release.

Read this too: https://wiki.ubuntu.com/Testing/EnableProposed