Sequence of artists in Music library browse view is incorrect

Interesting. It almost looks like your artist names are not using regular “A, B, C” but some other things that looks the same. PMS can track these characters differently, which could be why you see the list repeat. Can you try taking the first one “Aerosmith”, edit the entry and retype “Aerosmith” to make sure it is using regular characters and see if that moves to where the other "A"s are?