No, this wasn't obvious at all, specially since it wasn't working the whole way.
We have now released a fix where filtering on empty usernotes and 0 finds works properly. Finds can be filtered on the number of finds one has logged for the cache. So, it's best filtered on 0 for not found, and > 0 for found. If you use 1 for found, you will miss those that are double logged (rare case, but still).