Hi @Marie101, I've just experienced the same issue. I called Airbnb and they informed me that this only applies to users with reviews, not new users who have no reviews. Therefore a brand new user can book using Instant Book!
This is not how the setting is worded as you point out:
"Require guests to have recommendations from other Airbnb hosts AND no negative reviews."
If it said "or" I would understand that a new user with no reviews (negative or positive) could book instantly though.
The Airbnb help article on the setting clarifies the actual function of this setting though:
"Recommendation from other hosts: You can limit bookings to guests who’ve travelled on Airbnb and received only positive reviews from other hosts."
https://www.airbnb.co.uk/help/article/484/how-can-i-control-which-reservations-i-get-with-instant-bo...
That is clear and makes sense to me. Not sure why the wording differs on the actual settings page. I am going to submit a bug to them, you may like to do the same:
https://www.airbnb.co.uk/help/feedback