Hi
My windows were the same in our previous van.
I found it helped to find out what side the locking mechanism was on, and always push the window up fully on that side as opposed to pushing up in the middle of the window. This seemed to get the last centimetre out of the locking arms and worked most of the time.
I admit it didn't work every time and every now and then there was a window which would just play silly beggars for ages.
It always went wrong when you were in a hurry, or wanted to shout at the kids.
Dave