I think it does not bode well for supporters of Medjugorje that it is being investigated now. Usually the Church waits until an apparition event has completed before moving to make any statement in favor or opposition. This is simply because if the Church approves the apparition and later statements by the visionaries conflict with Catholic teaching, then the Church would have to revise its statement (and would have egg on its face). The fact that they are moving before the apparitions have ended suggests that they have already heard enough to make a definitive judgement, and that the judgement is not going to be supportive of the apparitions.
But time will tell, and I hope and pray that all Catholics – both those supportive and opposed to Medjugorje – will submit to the authority of the Church in this matter.