Append queries problem

The queries reference local files, so I can't try resolving this in the Query Editor,

But if you create a calculated table based on your two source tables

Union Table = UNION('Data_ISS ECP','Data_Lo''s WAS')

That looks like it works just fine to me

Edit: I also see the following in the applied steps (again, can't see the data to confirm) but it looks like it might be part of the issue.

For the "Changed Type" step in both tables, the date column is handled differently. For ISS ECP you have 

= Table.TransformColumnTypes(#"Promoted Headers",{{"Month", Int64.Type}, {"Date#(lf)", type date}, ...

And for Lo's WAS you have

= Table.TransformColumnTypes(#"Promoted Headers",{{"Month", Int64.Type}, {"Date", type date}, 

It looks like you tried to modify the type for Lo's WAS but not ISS ECP. and Lo's WAS has a slightly different date name (Date#(lf) instead of Date). Pretty sure the #(lf) stands for 'line feed' and is one of the hidden characters I was referring to in the last post.