Power Query: List.Max doesn't work on Date

Old thread, but this is/was available on the Ribbon also: Transform tab > Date & Time Column section > Date > Latest 

It generates the same M as in this thread:

= List.Max(Source[Date])

This has been answered but the steps are not fully clear, for the New Power BI User I will break down the solution:

There currently is NO data type of "List", just make sure you have the column as Data or Number.

Here is where the confusing part comes in as the actual "List.Max()" function isnt complete in syntax you either have to know exactly how to code it or you need to make an adjustment in Advanced Editor Section to manualy type in the previous Query Step Name as "Table" reference.

I create a new Column I type the following in the column formual page "=List.Max({INSERT COLUMN NAME})" Add Column 

THEN I go into Advanced Editor and Copy the Query Name from the prior step in the front of my INSERTED COLUMN NAME.

BEFORE:   

#"Changed column type" = Table.TransformColumnTypes(Navigation, {{"ci_item_time", type date}}),  #"Added custom" = Table.AddColumn(#"Changed column type", "Custom", each List.Max([ci_item_time]))

AFTER:   

#"Changed column type" = Table.TransformColumnTypes(Navigation, {{"ci_item_time", type date}}),

#"Added custom" = Table.AddColumn(#"Changed column type", "Custom", each List.Max(#"Changed column type"[ci_item_time]))

NOW if you knew what your prior Query Step name was you could have manually coded this into the New Column Formula statement like List.Max(#"Changed column type"[ci_item_time]) I hope this clears up any confusion on this Topic.

E I L O O P

your column type is List? That function is to find max in a list or use groupby function to get maximum date.

Whats the context of the power query line of code?  Are you passing a column or list type to the function?  The error message reads like you have passed a since value of type Date.