Thanks for the response.
I'm not sure what you're suggesting, I think the sorting and grouping settings were global. However, this issue occurs in all views (except track details, of course). The thing is, in theory, no matter what the other tags are, if the values on a field selected as “to define an album” are different, then those tracks must be grouped separately. Am I understanding this right, or are there other factors involved?
If this help, my virtual tag <¿Lista, Vinil-r?> has a numeric value, which is assigned by reading the first three characters of the tag <Grouping>, and a series of conditionals depending on its content. The tag <¿Lista, Vinil-r?> has its values as expected (the highlighted column in the above images), yet, they remain grouped together.
Now, I've looked with more detail and it seems that for some <Album Artist> it works every time (Radiohead, Blur, Beastie Boys), and for others (the most) it never works (Rage Against the Machine, Garbage, Beck, Korn, Sonic Youth), as far as I can tell, tough I haven't looked to all of the relevant artists… (The songs that I’m trying to exclude, belong to a 90s compilation, and I don’t want to have duplicated songs for those albums I have separately).