Unable to sort by fullName when formatted as "lastName, firstName"

[tnguyen]

Hi, new to FusionAuth, and having a basic issue of getting the list of users sorted correctly. My instance is v1.61.0 and using OpenSearch 2.11.0.

I have some local users which I added through admin UI. Each have these fields populated:

• email
• phone number
• user name
• password
• first name
• last name
• full name

The fullName field is formatted as "lastName, firstName". When I search for all users and sort by fullName, the list is always coming back descending order (Z...A), regardless of the sortFields[n].order value. This is happening in both the admin UI and the search API.
Note: I found that if I format the field as "lastName.firstName" (using "." instead of ", "), then sorting works correctly.

I haven't customized the instance very much beyond the first-time setup, so I don't think I've changed anything that ought to affect this. Is there some place I can debug further about how it's trying to do the sort?