Matte not rendering

I have footage of hands closing a laptop.
Im trk’ing the screen for a replacement.
the hands go in front of the screen, when it is closed.
Im trking the hand/fingers , have an edge around fingers, so the replacment
laptop screen stays behind the hands, when they cross in front. all looks good.

but Im only seeing the screen “matte” after the export, it is not cuting the hole when the hand passes in front, I DO see it on monet while I work, but is not exported. I must be doing something wrong.
Im using 2 layers, one for the screen and one to track the hands

Ollie