thats probably because you check all options in the optimizer. Instead you should check only the options that fix the issues with your model - the ones that sanity test shows.
And about the shaded parts - are normals broken? or materials with checked/uncheked tags? or light nodes?
And about the shaded parts - are normals broken? or materials with checked/uncheked tags? or light nodes?
I have no idea how to use it, but I know me using it breaks my stuff. That is why mostly RexusMax helps me with that.