I have created a survey and have created several unique URLs that I intended to distribute to others to test the survey.

I have configured survey category to be public, survey access is marked as public it is not marked as a private survey and both category and survey are published. However, when I try to access the URL I get the error 'You are unauthorised to respond to this survey' whether or not I am  logged in to the site. Below the message is a the word Categories with a folder icon.

Can anyone please suggest where I'm going wrong ?