If I use the
siunitx package to generate an imaginary number e.g.
then it places a 0 before the 120 (probably some artifact of expecting complex notation with a real number included).
This seems like a bug. Also it puts the number in parenthesis which would make sense if it was a complex number with a real and an imaginary component, but not if it's just an imaginary component on it's own.
I have considered turning of parsing, but that can create other formatting problems e.g. I like my "i" to be italic", which can be set up with the options, but not if parsing is turned off.