it seems to me, but maybe I am out of topic, that complex chord as e.g. parts I tried to use here are recognized partly as real chords, and part as single notes, where the latter are useless ans must be removed before searching for useful chords in the remaining
it can explain why apparently simple song as e.g. Cream’s Strange New Brew, John Mayall’s Oh Pretty Woman, and Mountain’s Flower of evil were not recognized