Putting this question here in case it helps someone else, or in case anyone else knows the answer! @Benedict King, a minor 7th tetrad (triad with 7th) in a major key has a flattened 7th right. E.g. in C major, the II in Dm7 which is D,F,A,C. But in a minor key, would the tonic tetrad still be a minor 7th? I am so used to minor tetrads always being m7. I would expect though it to be a major 7th because the 7th in a minor key is not flattened, e.g. in C minor the 7th is B not Bb, so surely the I tetrad in C minor is Cm#7. Or how else would you notate that? CmM7?! This can’t be right!