sorting results by publication date
The sort by publication date newest/oldest in Summon does not sort by the displayed publication date but by the merged record date which is invisible to the end user.
The user is seeing the results screen and so it seems really odd to provide a publication date sort and then not allow the user to sort by the date that they can see since the behavior on the backend is entirely and completely transparent to them and doesn't seem to serve the user well by any stretch.
There needs to be a true publication date sort that uses the displayed publication date rather than relying on the invisible dates that only visible to catalogers.
This feature was added as part of the upgrade to the Central Discovery Index (CDI).