Hello @leslie_irvine, @mattias_alveteg, and @Olaf_ ...
Full disclosure... I am a Canvas admin for our College's Canvas environment, and I do not teach course. So, my experience using the Gradebook isn't as strong as those that do teach courses in Canvas. That being said, I would like to try and offer some insights...
First, it is unfortunate that Leslie's question has been unanswered. There may be reasons for this...including that she may have stumped Community members with her question. So, it is possible that folks here in the Community don't have a good solution to suggest...and thus it has been unanswered.
Next, as you know...Excel is all about rows/columns/cells of data. Based on the screenshot that Leslie has provided in her OP (Original Posting), I am assuming that the grades she is asking about are in the columns labeled "Critical Re"...as those are the ones that have zeros for student grades in the CSV import image. When you set up an assignment in Canvas with a "Complete/Incomplete" designation, you can also specify the total number of points possible for the assignment. For example, in my screenshot (below), I have set this assignment at 10 points, but I have also set it with the "Complete/Incomplete" setting.

As an instructor, when I grade this, assignment, I have the option of choosing either "Complete", "Incomplete", or "Excused". For this example, I chose "Complete" for Frodo Baggins, and it automatically assigned him 10 points (at least, in the CSV export) because that is the total points I had assigned to the assignment when I created it. In the Canvas Gradebook, I see the green checkmark (as you've described).
In your example with the "Critical Re" assignments, it looks like you've set the total possible score to zero. And, even if you then mark a student's assignment as "Complete", it will fill in a zero because that is the total possible points you set for the assignment.
I completely understand how having some other marking in this column in the CSV export would be more desirable that showing a raw score. The programming to have some kind of image (such as a check-mark instead of a number) is not in my scope of knowledge, and I'm not even sure if a CSV export could include images in Excel tables...if that was desired. As a thought, you might want to consider creating a new Feature Idea here in the Community so that other folks have a chance to evaluate it and see if it's also something they'd like to see implemented by Instructure.
I hope some of this will be of help to you. Please let Community members know if you have any other questions about this...thank you.
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