Group By function causing issues in Power Query

[OliverBrown02]

An error appeared in one of the Power BI Reports used daily within my business. This report has been running and refreshing successfully for over a year. However now when refreshing this error appears.

After doing some digging in the Power Query Editor, I have found an error being caused by the "Group By" function,

Has anyone encountered this, and know how to resolve the issue - the other "Group By" functions in other tables are showing the same error message.

[Anonymous]

Reza from Radacad has a great example:

Make Your Numeric Division Faultless in Power Query - RADACAD