The two shortcuts, VAssistX.RefResultsNext and VAssistX.RefResultsPrevious, seems like they only works when focus is inside the References Results window. Aren't they suppose to work anywhere?
In the IDE options dialog, in the keyboard mapping, what scope do you have for these two shortcuts? I have just tested them with the scope set to Global, and they are both working correctly for me in VS2008 and VA 2023. I have tested with focus both in the editor and in the Find References Results window.