Focus behavior; result is outside specified Genre

I try to use Albums / Focus to make a selection of 70’s pop, and all sorts of stuff comes up. Metal, proto punk, prog-rock etc. No Pop in the labels of the album or the artist, no sub-genre of pop, no visible link whatsoever. I tried to simplify and just focus on Genre ‘Pop’; same result.
Can someone tell me what to expect when using Focus? Maybe I just don’t understand what it’s supposed to do.

Hi, I do have Pop in the genres, but the entries are not very reliable. For example Jeff Beck with the Jan Hammer Group live has been marked as Pop, other Pop songs are missing.

it’s all in the subgenres. Indie Rock is part of Pop/Rock is part of Pop. So Rock morphes into Pop. Silly choices.
So I went through all sub genres of Pop, 5 levels deep, and removed all qualifications not to my taste. On 10K+ records. Took a while…