It never ceases to amaze me that with all the time I have spent developing web pages new and mind boggling foibles are waiting to bite you in the rear.
I had a simple HTML form with a onchange=”this.form.submit()” on a select drop down which was not submitting when the value was changed. The form was structured correctly and the page was validated against the doctype. After a few minutes on Google I had my answer, do not name the form submit button “submit” because it conflicts with internal form properties. This page gives more detail in the “additional notes” section.