Need help with M-Query in Advanced editor

Hi, Anonymous 

Based on your description, I created data to reproduce your scenario.

Source:

= Table.FromRecords(
        {
            [Data={null,#date(2020,1,1)}],
            [Data={null,#date(2020,1,2)}],
            [Data={null,#date(2020,1,3)}],
            [Data={null,#date(2020,1,4)}],
            [Data={null,#date(2020,1,5)}],
            [Data=#date(2020,1,6)],
            [Data=#date(2020,1,7)]
        }
    )

You may add a new step as below.

= Table.TransformColumns(Source, {"Data",each if _ is list 
then List.Max( List.RemoveNulls(_) )
else if _ is date 
then _
else null
}
)

Result:

Best Regards

Allan

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