Yep! same problem here........however, I have been able to figure a way to lift it up with only a slight adjustment. Main thing I found : is to make sure you are grabbing the seat and not the outer frame when you start to lift -----that way your fingers will keep the cushion from sliding back. If you quickly grab the outer edge, then you're going to tip the whole frame a little and that gets teh pad sliding.
It was aggravating at first, but, I spent some time 1 morning just practicing (probably looked like a moron to the squirrels ( "up..down....up ...down" )