In certain situations, editing the settings for a scheduler which has grading enabled, and where grades have already been entered, can reset the scheduler to "no grades" mode. Editing the settings again, and setting the correct scale, the previously entered grades will reappear.

Steps to reproduce:

Cycle 1
Select "Edit settings" for a Scheduler instance

Set Grade type as "Point" and Maximum Grade as "2" (for example)

Save and display

NOTE: Previously entered grades are shown as expected

Cycle 2
Select "Edit settings" again

NOTE: The Grade and Maximum Grade are set as expected.

Set Grade Category as  "Webinars" (a category in the gradebook)

Save and display

NOTE: Previously entered grades are NOT shown

Cycle 3
Select "Edit settings" again

NOTE: The Grade and Maximum Grade are shown as NOT set.
Repeat steps from Cycle 1 above … this corrects and restores the grades
Reproduced today on current master (3.3rc).