We use the NumNonClothing section number to iterate in the sections, this is an error if the cloth sections are not at the end of the sections array. See the following picture of a search on NumNonClothingSections API usage in the code. We have to fix all iteration to use a proper logic.
The polygon count in the viewport is not anymore counting all the non clothing section polygon
The polygon count is all section polygon minus the clothing sections
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-77953 in the post.