OK, this happened to me 2 times today already- I set my raid boss to public, later I come back and the button is "off" and then I need to resend links via private messages, royal PIMA WTF is going on? It seems to me, if I send out regular Coop Boss in the mix is causing this problem.
O.K. this just happened again and verified upon opening new coop boss it turns raid link off, and yes I turned public sharing on for my coop boss as well.