One of my users just reported this one to me. Shortcuts are definitely enabled and working in general, and 'j' and 'k' work correctly on the search-results page, but for some reason not when trying to page through the issues returned by the search. The 'up' and 'down' buttons work, so it's not a problem paging, it's just the keys that aren't working.
Rather oddly they *are* working on our development JIRA system, which has what should be an identical setup - same config, same plugins and so on. It's only the production system that's doing this.
I can't think of what could have caused this. The problem exists in multiple browsers (tested on Firefox 21 and Chrome 27). Can anyone shed any light, please?