Error: Import unsuccessful: TypeError: Cannot call method "toLowerCase" of undefined.
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at gs/Classroom Import v2 (GradeBook for Google Sheets and Classroom):221 at gs/Classroom Import v2 (GradeBook for Google Sheets and Classroom):221 (updateBook_v2)

This has now been fixed in version 1.85. Have you been able to test it?
Hello. We are currently working on this issue. It will be fixed as soon as possible.