This is a hypothesis i've been working on, so take it with a grain of salt.
I believe that there are 3 states for monthly reporting. On time, not reported, and late.
On time is good
Not reported is good
late is bad.
I believe though that the "not reported" is simply a blank field. A null if you will. And I believe that if a month previously had a "on time" or a "late" reported, the null does not always override the previous reporting properly.
So your score is calculated as having no lates, but whereever you are looking at the report still has the old information.
The same can happen the other direction. A late is rerecorded as "not reported", but the actual scoring is still low because the 30d information wasn't overwritten properly.
