I have been searching solution for this for few years now.
I'm currently using Python script within alteryx to work around this but clunky at times.
I hope alteryx does something to support this file type. Reality is that legacy platforms still output ".xls" files and that will not go away soon.
If systems are updated and output .xlsx we wouldn't need to do any transformation in Alteryx right?
Can you share your workaround on this .xls limitation?