I can confirm this bug. I also use Ubuntu 20.04. I noticed, that it happens every time, when apt has an update, that isn't visible through the graphical frontend updater. If this is the case, the update notifier pops up with the message "System is up to date". If I than do "sudo apt update", apt shows me, that there is an update available. If I install this "invisible" update, the update notifier is calm again, e.g. the message "System is up to date" disappears.
This problem started after the introduction of Ubuntu Pro. It must have something to do with it.
Please, fix this bug.
I can confirm this bug. I also use Ubuntu 20.04. I noticed, that it happens every time, when apt has an update, that isn't visible through the graphical frontend updater. If this is the case, the update notifier pops up with the message "System is up to date". If I than do "sudo apt update", apt shows me, that there is an update available. If I install this "invisible" update, the update notifier is calm again, e.g. the message "System is up to date" disappears.
This problem started after the introduction of Ubuntu Pro. It must have something to do with it.
Please, fix this bug.