Giving users/groups roles via UI aren't being saved and/or aren't appearing

Summary: After creating a role or group and assigning it one or more permissions via the UI, the permissions do not show up in the list view or detail view

Repro:

1. In UI, go to "Security"
2. Click "Add User" or "Add Group".
3. Enter user information
4. In "Roles" are on right side, select one or more roles.
5. Click "Add User" or "Add Group" to save.

Expected:

The selected roles to be saved to that user. The selected roles should appear in the list view. The selected roles should also appear when going back in to edit that user.

Actual:

The selected roles are not appearing in the list view. The selected roles are not appearing in the edit detail view. Based on a REST request, it doesn't appear that the assigned roles are actually being saved at all.

Notes:

See attached screenshots.