Issues with rating averages

Today I was messing with the "Releases" feature and came across an album with only two ratings, one of which is my own 2 star rating and the other is a 5 star rating, yet the clan rating is also 5 stars. The album in question is Abyssic - "A Winter's Tale" (2016). The album is in both the Guardians and The Fallen, so at first I thought it was just picking up the Guardians average rating, and assumed the other rater was a member of the Guardians, but further exploration reveals that actually neither of us who rated it are in the Guardians and both of us are in the Fallen. The site rating is correct at 3.5, which is also what the clan average should be. Any explanations for this discrepancy guys?