Hi Maverick, 

I built a survey in one of three categories, a category that is open to public. 

I made this survey private and anonymous, so it can only be filled by someone with the link to the survey. 

I have a menu, called "enquetes" (=surveys), that is pointing to the list of categories. 

This menu for now is not visible for the public, it is only visible for people who are registered, so more or less hidden. But it appears that when giving the global link to someone, he/she cannot fill in the survey, the site requires to login. 
When I change the access of the menu enquete to public, the link is useable. 

Is this the intended behaviour? As I would expect that the menu permission would not play a role in the access to the survey. It took me quite some time to find how this worked. 

Cheers, 

Jim