auto-package-update does not upgrade all the packages that should be updated

[Sbozzolo]

Hello,

I have noticed that auto-package-update misses many of the possible updates. For instance, today it is my update day and the script didn't find any new update, but running package-list-packages I know that there are new available upgrades.

Am I missing something? Maybe I have misunderstood the purpose of this package....

I am using GNU Emacs 25.2.1, on Arch Linux fully updated.

I can provide any further information if requested.

[rdiez]

I have noticed a similar problem, which may be the same issue.
Emacs 28.1 comes with built-in package xref.el version 1.3.0, and ELPA has already version 1.4.1.
The package manager offers no update, but I think it should make an exception, and consider ELPA packages to be upgrades to built-in packages.