I do not have access to the file. however after further testing it seems to flow through when the half slab is acting as the top slab.
When i place water to fix the water line on the outside of the structure it is ignoring the fact that there is a half slab there.causing water to flow into the structure its self.
I do not have access to the file. however after further testing it seems to flow through when the half slab is acting as the top slab.