I checked the problem and yes, the actual issue is:
GSX starts a pushback ignoring the parking brakes status after exiting from the QuickEdit pushback.
It's not related to a specific airplane and it only happens when using a QuickEdit pushback for the first time after having just edited it. Using a previously saved QuickEdit, or a pushback customized with the editor, or a default Left/Right pushback, or a Straight pushback, works normally.
So yes, as with any reported but that can be replicated, this will be fixed as soon as possible.