Pat, I just tested in a blank drawing with a freshly drawn spline and PEDIT, and it converted the spline without keeping the original.
You would need to send in an example spline in a ticket with the exact steps you're following for me to see if I can replicate to help troubleshoot further.
How to Submit a Technical Support Ticket
You can also try the alternative command, SPLINEDIT, to convert it to a polyline.
-Amanda