According to the syntax of DATEIFF function, start_date and end_date should be a scalar datatime value. Scalar value means it’s a single value but not something like a column or table. For more details about DATEDIFF, please refer to DATEDIFF.
Please try to replace the part of DATEDIFF as the following:
DATEDIFF(MINX('Table','Table'[Start of Week]),MAXX('Table','Table'[End of Week]),WEEK).
Then you will get the count of weeks between every start data and every end date.
Community Support Team _ Caiyun
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