What you were doing when the issue happened
Play any unrated song on my iPod/iPhone in iTunes (iTunes 12.3.0.44), open Alfred iTunes mini player, rate the song. Alfred iTunes mini player shows the song's rated has been changed, but in iTunes, the song's rating is not changed.
Whether you were able to replicate it a second time by performing the same action
Yes.
Include any screenshots that might help us
Sorry I don't know how to attach images.
Include the Alfred version & build number you are using
Alfred v2.8 (414).
Include your OS X version
OS X 10.10.5