Panning stopped working

I’m running Cubase 5.5. Panning mono tracks always worked until a few days ago. Don’t know what I did, but it effects projects I haven’t edited in months, so it’s not related to a single project. I’ve read the doc & searched the forums, but no luck so far. Has anyone had this issue?
Thanks
Jim

Hi and welcome,

Try Safe Start Mode or trash preferences of Cuabse, if this helps.