There's three categories for reports, "good", "bad", and "unhandled".
Your accuracy only calculates based on good/bad ratio, and ignores unhandled.
The "Unhandled" status can come either from nobody taking care of your report yet, or from the moderator looking at your report not knowing whether they should mark it as good or bad.
reference:
"Unhandled" means that every moderator with jurisdiction over the post was unsure about the correct thing to do with the post and so left it for other mods to deal with, but no mod ever decided to act on it. I suppose it can be thought of as a "weak bad", though it's ignored for your accuracy percentage.
