Asset UPnP R2024 beta.

[Arnold]

The description of this new option "Fill missing Artist tags - Affects files with Album Artist but no Artist set" is a little cryptic for me, because all my albums have also artist tags.

Ah, I now understand how this works.
Asset just performs a hardcopy of the AlbumArtist tag to the Artist tag. And it doesn't matter if the artist tag already has one or more entries, Asset just appends another entry.
And with this option switch off, Asset does not copy (and append) the AlbumArtist tag to the Artist tag.