Steps to replicate:
1) Create Gradebook Item called "Week 2: January 22 - 29" and make it worth 10 points
2) Use Export functionality
3) Use Import functionality
The failure will produce generic error in UI and no error in logs: "The file you uploaded was not formatted correctly."
The problem is that the regex is very strict:
final static Pattern ASSIGNMENT_WITH_POINTS_PATTERN = Pattern.compile("(\\w+ \\[[0-9]+(\\.[0-9][0-9]?)?
This regex is only allowing a-zA-Z0-9 so any special character like hyphen or colon causes import failure