"bewildered, puzzled," by 1847, past-participle adjective from mystify.
Entries linking to mystified
mystify v.
1798, "to make obscure, obscure the meaning of;" 1814, "perplex purposely," from French mystifier (1772), a verb formed irregularly from mystique "mysterious" (see mystic (adj.)) + -fier "to make" (see -fy). Related: Mystified; mystifying.