The cutting force on that cutter (210) is much lower than a regular Graphtec Ce6000-60 (450) . Or even a value cutter. which has (350) Maybe that could be the problem. I have never cut mylar, I am just looking at the specs of your machine. Maybe it is just not possible with that cutter.
Compatible Media for Cutting Marking films (PVC/fluorescence/reflective) with a thickness of 0.1 mm or less, excluding high luminance reflective films
I don't know of anyone on here that has a CE lite-50.