Hello,

1. Create assignment, use point scale and set maximum grade from 100 to f.ex. 6
2. Return a f.ex. online submission as a student
3. Review and grade the student submission f.ex. give the student grade 4
3. Edit assignment options and add another submission type f.ex. file submissions
4. Save settings and return to assignment options
5. Notice that maximum points have now been automatically changed/reset from 6 to 100 and student now has grade 4,00/100,00. Also notice that assignment tells you:

"Some grades have already been awarded, so the grade type cannot be changed. If you wish to change the maximum grade, you must first choose whether or not to rescale existing grades."

Affected version: Moodle 3.1.1+ (Build: 20160728)

I think this is a major one, assingment changing maximum points by itself.