I know many solid Catholics and priests who are convinced that Our Blessed Mother is appearing in Medjugore. The Holy See has not made a determination and so we are free to do so.
I admit to being very curious when I first heard about it but I became skeptical early when when of the visionaries lives (or lived) in the North End of Boston claimed Our Lady rearranged her appearance when a time conflict arose in a local parish. The traveling circus shows like this one deepen my convictions but are certainly not the only reason I am a skeptic.
It feels like the Holy See has been dragging its feet but whatever their judgment, I trust the decision will come in God's time.