There's a room with yellow water and big blocks in each axis a few rooms after placing the 6th hypercube. If I'm reading the puzzle right, you turn on a white toggle barrier to get the water to the yellow side of a yellow/green, which is meant to then drop on to an orange/purple, be redirected with the remaining two yellow blocks, then run over the red/blue to the water wheel. In my instance, there's sufficient gap between the yellow/green and the orange/purple that the water drops through. I don't seem to have any save before this, and it's possible auto-save wrote over my manual save.
There's a room with yellow water and big blocks in each axis a few rooms after placing the 6th hypercube. If I'm reading the puzzle right, you turn on a white toggle barrier to get the water to the yellow side of a yellow/green, which is meant to then drop on to an orange/purple, be redirected with the remaining two yellow blocks, then run over the red/blue to the water wheel. In my instance, there's sufficient gap between the yellow/green and the orange/purple that the water drops through. I don't seem to have any save before this, and it's possible auto-save wrote over my manual save.