I am sure I have reported this before, but with Hookpad adding different colour modes it is time to bring this bug to attention again.
The viio/i chord has no colour assigned to half of the stripes in the Minor key, because this colour scheme requires a ♯7 in the Minor key. A similar bug also occurs when a supermodal chord contains ♭1 in the bass.
http://puu.sh/lII7s/2b0cb2941e.png