SD 7.5: Can't Work Incidents in Firefox

Has anyone else seen this? I can not work an incident in Firefox on either OS X or Windows. I've tried FF 23 and up and when you click on the "Work Incident" link the page opens but remains blank. We haven't made any major modifications to the system at all. We are running 7.5 SP1 and didn't actually test it prior to SP1 (working an incident from FF).