control: severity -1 wishlist I've now seen the error of my ways. Downgrading the severity to "wishlist" since it appears to work as documented but not in the way I'd find most useful (and since there doesn't seem to be an "invalid" tag).
My mistake was to specify the same positive priority for all versions of the pinned packages. This downgrades the priority of the installed version as well. The reason some packages were still not upgraded in the example shown is that the pinning allowed versions from backports to be considered, and some of these were then held back due to their own dependencies. What I'd like to have is a way to lower the priority of versions other than the one currently installed, without having to explicitly configure a version pattern. Yes, setting a hold on the package (or a negative pin priority) covers most of the associated use cases. Most but maybe not all?