Course Builder/Lesson/Assignment/Task List reorders tasks when list reaches 26+

### Reproduction Steps

+ Created a Course, added a Lesson, added an Assignment, made that Assignment a Task List.
+ Added 26 Tasks to the List, Course Builder labeled them a-z
+ Added Tasks 27-31.

### Expected Behavior

+ Course Builder would label Tasks 27-31, as Za-Zz, or perhaps Z1-Z26

### Actual Behavior

+ Course Builder labeled Tasks 27-29 as A, and shifted them to the top of the task list
+ Course Builder labeled Tasks 30-31 as Y and Z respectively.
+ This caused the Task List to shift order when logged in as a Student.
+ Otherwise was still able to complete and submit the assignment.

### Error Messages / Logs

+ Include any relevant error messages or log files
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Potentially related, the blue Save Changes button on the bottom of Course Builder read as "Changes Saved", but when I hit the exit button, Chrome warned me that "if you leave this page some changes might not be saved"

```

### System Information

System Report

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N/A

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### Browser, Device, and Operating System Information

+ Chrome, MacOS