Steve Bugg reported a problem with the Survey that I think is now fixed. (Could not Submit at the “I am not a Robot”).
If you completed the form and could not SUBMIT or did not get the Form Submitted confirmation, please go back and retry the form now.
THE PROBLEM (for those who want to know)
I am sorry for the problem. It was not visible or obvious in form design or testing.
At the end of the Survey there was an “I am not a Robot” check button. This was not in the original form and did not show up in testing or with the initial responses.
Apparently Google adds this at some time AFTER the form is released. It is not visible or an option to delete in the form design. There is a large complaint area in the Google Forms Forum. Many people with the same problem.
Fortunately there was also a work-around that seems to work.