Help with solid element operations

https://preview.redd.it/ro6hp0yu1xlh1.png?width=779&format=png&auto=webp&s=f60b1a19c03a5d4e0a2551a0ab97283cd9d7714f

I have attached an image showing the problem. The foundation in the axonometry is not showing the slabs despite using solid element operations on it. Anyone who can offer some advice would be greatly appreciated.