When entries (albums, tracks, artists, groups...) are sorted by a given tag in ascending order, the entries for which the tag is empty are displayed at the top of the lists / views.
This is not a good behavior from a user experience perspective.
Just an example. In the screenshot below the albums are grouped by decade in ascending order, and the group which contains albums without a specified year appears at the top of the list ("Unknown Decade"). Not very nice...
This behavior is of course everywhere in the program. Just another example, in the column browser, the [Unknown] entry appears at the top of the list in ascending order, as soon as the tag is missing for an entry:
I know that for a computer scientist or simply any Windows power user, empty entries are always sorted before anything else in a list in ascending order. But it is not about compliance with computer conventions but improvement of the user experience.
There can be many situations when we want or have to leave some tags empty, for specific purposes. And sometimes we just haven't found the right info to put in the tag for an album, a title, etc. Displaying the empty entries in first position is as if the program constantly shows us the tagging gaps first, and this is not nice. By definition, for a simple end user of the program (and not a "tag administrator") these are just irrelevant, not specified, entries. As a simple user, if I want to sort my albums by a tag in ascending order of course I don't want to see the albums without the tag in first position
So, when sorting / grouping in views and panels (the user interface), always leave entries with empty tags at the bottom of the lists should be IMO at least an option. The desired behavior is implemented for example in the tables in AllMusic.com. In this page: https://www.allmusic.com/artist/the-beatles-mn0000754032/discography/compilations
Sort the table by the Year column. There are many compilations without year indicated in this table, and they remain at the bottom of the list. The other behavior would just be painful.