Expression results in Applied Steps in Power Query does not seem to comply with M script execution

[Anonymous]

I have written a M script to run a dynamic SQL query using parameters on a Direct Query. The script is based on this tutorial example (https://learn.microsoft.com/en-us/power-bi/connect-data/desktop-dynamic-m-query-parameters).

The M script works fine with parameter input from the slicers, and the generated dynamic SQL query return data correctly to the table visual. However, some results of the M script expressions in the Applied Steps in Power Query does not seem to comply with actual result/execution of the M script. The same goes for the dynamic part of the generated final SQL query expression. It seems to me that only the single-select and boolean value result of expressions are shown, but not the multiple-select value results (shown only as a double quote (''). 

It may be a logic explanation that I have missed here but it would indeed be helpful for unexperienced script editors like me to have a complete documentation of the results from M script expressions as a debugging assistance in the Power Query Editor.

[lbendlin]

Your M code looks a little convoluted. You can simplify that.

Passing Any Arbitrary Value From A Power BI Report To A Dynamic M Parameter (crossjoin.co.uk)