TDD - ajax button form submit via FormTester - Wicket 6

Dear Forum,
I am testing a form with has fields with ajax behaviours and form
components. The form has an ajax submit button to do all the necessary
processing.

Initially half of the form fields are hidden.

I then select a drop down list with has an OnChangeAjaxBehavior attached to
it in order to make the necessary fields visible and some, required.

I do it thus:

I then go on to set values on every field on form, including the ones nested
inside formComponents. Here are a few examples:

Finally, I submit the form, which is where the issue lies.

Initially I was calling

But I came to the conclusion that if I am using an ajax button I should call
tester.executeAjaxEvent. Therefore I have placed the following line before
the formTester.submit() call.

When I call it returns true. And after iterating through the code with the
debugger, some of the required fields have the following feedback messages:

Why would the above behaviour occur? What am I missing in order to make a
successful form submit?

I am really at a loss, since I have populated the necessary fields, as shown
on examples above.

Thanks in advance,
Lucas