Moodle 3.3.2+ (Build: 20170922)
When trying to enter grades, whether overriding or not. Entering grades using the "Five Point Letter Scale" I get the behavior shown in the graphic, and the totals. Both issues are highlighted in Yellow.
If I attempt to add a B to anyone with editing on, it immediately converts to a C when editing is turned off.
If you notice the column total also appears different with editing on vs. editing off.