Contacts displayed in wrong letter grouping

I changed the contact list to short and display First Name, Last Name. The sort is totally messed up now. Under “L” I have H R (first last initials), then I L S, then D I B, I S, I S, I & O, etc. Makes no sense for being in the “L” grouping. So I set it back to Last, First sort order, then back to First, Last sort order, and now it is displaying properly. Weird.