Member parent not showing up in unit records?

We have a long-time less active member who we've been trying to locate, but her contact information is no longer valid. I noticed that under the "Family" section her father (Billie) is listed as being a member, and it has his unit number next to his name. I clicked on the hypertext of the Unit Number to get Billie's bishop's email address, and emailed the Bishop asking if he knew Billie and if he could provide his less-active daughter's current address to us.

However, the bishop responded that he had never heard the name, and he even searched the entire stake directory and didn't find Billie. Any ideas why he would be showing up as assigned to a particular unit, but the Bishop of the ward isn't able to see him on his ward records?

Sometime odd things happen when records are sent out to address unknown. It might be a bug and that's his prior ward.

A name like "Billie" sounds like it could be a nickname or "preferred name" (field on membership record) instead of the full name. It's possible you're seeing the preferred name but the bishop is searching full names.