Simplifying shape does not function

Hey there,

I have a solid that has a lot of faces on the same plane that could be simplified. I tried using ShapeUpgrade_UnifySameDomain but it does not seem to be doing anything. I did some googling and spotted this post https://dev.opencascade.org/content/simplifying-shape. However it seems that the actual solution to the post has been lost (or i just am unable to see it).

and yes the shell is closed and all the planar surfaces have identical normal directions.

right now this is my code:

ShapeUpgrade_UnifySameDomain unif(shell, Standard_True, Standard_True, Standard_True);
unif.SetSafeInputMode(Standard_False);
unif.AllowInternalEdges(Standard_False);

unif.Build();
TopoDS_Shape smoothedShell = unif.Shape();

brepBuilder.Add(roughRoomShape, smoothedShell);

Does anyone have any idea how to resolve the issue?