Why would PowerSchool only import grades after a certain date?

Community Participant

I tried syncing my Canvas gradebook with our new PowerSchool system, and it's a mess.  Grades came out completely incorrect in the PTP gradebook.  It turns out, PowerSchool only imported grades from 9/25 and later; anything in my gradebook before 9/25, the assignment transferred, but none of the grades.  Any thoughts?