Music app: Songs not sorting correctly by artist

I want to list songs by artist in iTunes. I click on the "Artist" column when the "Songs" label is highlighted in the sidebar. Most of the list is sorted. But not all. For instance, seeing a group of songs by "Aaron Copeland" come after a group of songs by "Wynton Marsalis" makes no sense (screengrab provided if that helps).

Re-doing the sort (ascending or descending) does nothing to change the presentation order. Using Sequoia, 15.6.1, with Music/iTunes, 1.5.6.11. Any suggestions to fix this? Thanks for any help.