In this case I am fairly certain the curs.execute and commit need to be below the form_submit_button. Running the code the way you have it clears the app/form and then puts the list with empty values into the database. I use an if condition, e.g.,
if _submitForm:
curs.execute(…)
conn.commit(…)
This way these get triggered and run before the app refreshes itself on submit.