Boolean and Wireframe Modifier Interaction

Hi Jonathan, i have a problem which i wasn't able to ix on my own: Wenn adding the wireframe modifier my Grates inside the window (the boolean) disappears till i increase the thickness of the Wireframe modifier, thats all fine. But as soon as i enable the boundary option of the Wireframe Modifier, the grates disappear again. I can't seem to fix it.

Thanks for any help!