In my repository, I have set the first sort field to be "Creators".
On demo.dspace.org, the default sort is "Issue Date". This partially masks the issue that I am seeing.
- Search the repository or a collection by issue date
- Jump to a specific year
- Note the form parameters: "rpp=20&sort_by=2&type=dateissued&etal=-1&order=ASC&year=2015&starts_with=&submit="
- Select a different year
- Note the form parameters: "year=2014&starts_with=&starts_with=&submit="
Because of the default sort on demo.dspace.org, the results sort of make sense.
If you have a different sort order as your primary sort (such as creator), it will try to search creators by "year".