Design partition for Incremental compilation

I am using Quartus 18.1 and I am trying to do design partition for incremental compilation to save compiling time. However, I do not see the "Post-fit" preservation option for the netlist as described in the document. In stead, I see "not set", "synthesized" and "final" as options for preservation level.

Anyone knows how to select "post-fit" for netlist type in 18.1? Why is there such difference between the document and the tool?

Thanks