3D box mask not working in game

hello guys !! i hope you are doing great

i recently wanted to try to make a 3D box mask effect where the texture is different inside a BP Box. I have manage to make it worked in my viewport but as soon as i play the game the mask is not working. Do i need to turn on a specific parameter to make it worked or am i missing a render or a post process node for the effect to be rendered out ?
if any of you have an idea it would be suepr nice
i thank you all in advance :wink:

Isayux