EXCEPT statement generates a blank row

Hi,

I have a calculated column that has been generated from two other columns using an EXCEPT statement:

The calculated column contains one blank row I want to get rid of.

None of the input columns contains blank rows and both of them have the same data type - text hence I do not understand why the blank row is there. Also, since this is a calculated table I cannot remove the blank row with the power query because the table doesn't appear in the Power Query Editor view.