Always consider the possibility that your relative may be listed with only their initials in any document or record. Some individuals who did not necessarily prefer using their initials were still recorded without their full first or middle name anyway. Some census takers were particularly fond of using initials and the occasional newspaper editor resorted to using them as well.
My great-grandfather Mimka John Habben often went by “M. J.” My paternal grandfather, shown in the picture with his truck, often used just his as well–he also occasionally signed his name this way as well.