[elfnor]

@davidfor is right. All the books in the shortened folders are books of short stories with many multiple authors.

Only including the first author in the file name works:

{#folder:subitems(0,1)||/}{title} - {authors:sublist(0,1,&)}

For my 3 deep hierarchy of tags in my custom column #folder this works:

{#folder:subitems(0,1)||/}{#folder:subitems(1,2)||/}{#folder:subitems(2,3)||/}{title} - {authors:sublist(0,1,&)}

Thanks