''A mysterious ring is floating in the air''
You get that message when you have either fainted or caught the Pokemon inside it
So in conclusion you probably are just re-visiting one of your old mirage spots wher you fainted the previous Pokemon or caught it. Try another one or try again tomorrow.
Source: I tried it
Oh yeah and check the bellow comment ''Well I somehow fixed my problem, I'm not quite sure what I did but I talked/retalked to everyone in Sootopolis and in Pacifidlog.Whatever I did it triggered the portals into working :P''
commented by xmisslight
edited by ƒιzz