I'm not real sure if I understand your problem, Are you saying while it is cutting that the vinyl is not moving? Or that it does not move forward after the job is done?
the advance after plot command feature does not work on all vinyl cutters. Some cutters cannot read it. But make sure you have advance after plot clicked in your software, also note Flexi8.1 is not even Vista compatible, and was not Vista compatible til version 8.5, and your running it on a newer operating system than that.