Hey Famix,

Here is how you would do this:

Code (Text):

1. on any movement:
2.   if {nomove.%player%} is set:
3.     set {_l} to player's location
4.     set {_l}'s x-coordinate to {-lastPos::%player%}'s x-coordinate
5.     set {_l}'s z-coordinate to {-lastPos::%player%}'s z-coordinate
6.     teleport player to {_l}
7.   set {-lastPos::%player%} to player's location

As you can see here, instead of cancelling the event, I set their x and z coordinate to the location but keep their new y coordinate therefore allowing y movement.

I hope this helps!