Hi Psygorn
"Extend Edge Selection.js" has a couple space characters in its name.
When you run the script by typing its name in the input field or setting a shortcut key, it'll run the first piece of the name before the space character.
So, when you type "Extend Edge Selection", it will run the "Extend" command.

There is a simple solution for this:
Change the script name to something without spaces like:
ExtendEdgeSelection.js
or
Extend_Edge_Selection.js