The paragraph that says
Monastero San Pedro de Arlanza
is causing the problem. If you move that paragraph out of the list then it sorts OK but any sub-selection that includes that line will fail to sort.

I don't know why that one is different but if you toggle to view the field codes rather than the result you can see that line is formatted differently.

You can remove the hyperlink from that line and it will then sort.

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Andrew Lockton
Chrysalis Design, Melbourne Australia