5ish is referring to Tzanz and its offshoots such as Bobov.
Meno, they say shehakol.
Neville, no, it has nothing to do with it not being eaten raw. Plenty of vegetables are not eaten raw, but when they are cooked they are ha’adama. And Avram, he did not mean raw potato, which everyone agrees is shehakol. He meant cooked potato, on which Tzanzers say shehakol because the Divrei Chaim confused potatoes (kartofel) with truffles (tartuffe) and thought they are fungi.