I had the same problem - despite accurate grades in the attendance report, they weren't coming through to the gradebook. I finally fixed it by deleting my attendance activity and adding a new one, and changing the Grade from 100 to 2 when I created the attendance activity. Now the gradebook seems to receive the percentages correctly (with Present worth 2 points per session).
Attendance (plugin)
Attendance grades not appearing in Grader Report
This discussion has been locked so you can no longer reply to it.