What do you mean by "No longer"? Did it used to function properly and suddenly stop or did you change/upgrade/twiddle something?
There is/was a Graphtec firmware update and a corresponding Flexi 7 patch the addressed this very situation. But that was about 18 months or so ago and I'm not sure that your particular model was affected.
Clue: If the media size sensing returns exactly 1/10 the actual size in roll mode and returns the proper size in sheet mode, this most likely is the problem.