Required questions submitting blank

[EmilieJackson]

I've created a survey where all questions are required and dependent on the previous question being filled in in order to proceed to the next question. Today during the survey administration, there were 5 surveys submitted almost entirely blank which shouldn't theoretically be possible. I haven't been able to recreate the scenario where it would be possible to submit a blank survey after filling in only a couple of questions.

I've included photos of the blank responses and how the code is set up on the backend. 

[DougBrowning]

Could it be that the relevant is hiding the question?  Required will not trigger if the field is hidden by a relevant. You are hiding groups a lot so any question in a hidden group will not trigger the required.  Looks like if location is not filled out then surveyor is not show which then hides the next question which in turn hides respondent and so on.

The other thing that happens to us is people edit them in the web map or Pro.

Hope that makse sense

[ChristopherCounsell]

Can you share the XLSForm? Only way we can really confirm it it's robust.

Otherwise they could be on an older version of the form, before you required them to update it.

As @DougBrowning said very good chance that the users are entering data somewhere else. Check who created the features through editor tracking and ask them how they are doing it.