The undeniable miracle at Fatima

[Jehanne]

https://en.wikipedia.org/wiki/Miracle_of_the_Sun

What he's saying is that what was seen by all these people was in regards to the sun. Obviously people's descriptions/experiences may vary slightly, but that's the case anytime you're hearing an account of something from thousands of different people. 
The point is, if all these people were making up something or having hallucinations simply because they were "expecting" a miracle, then maybe one person would have said they saw the Virgin Mary... another would say they saw Jesus.... someone else may say they saw an angel... another person would say a flying pig, etc. You get the point. But all the accounts, which were thousands, were in regards to the sun changing colors and/or moving around in the sky, and all happened at the same time. I don't see how it is at all reasonable to conclude that all these people were having the same hallucination at the same time (which wasn't even the time they were expecting to see anything), or that they were all lying and somehow their lies all coincidentally happened to be the same.    
As for those who didn't see anything? To me, it really only makes it more convincing that this was a supernatural occurrence. Not everyone is gifted with being witness to a miracle. If the sun truly was changing colors and moving in a natural phenomenon, I assume everyone would have seen it.

A good assumption!  And, of course, astronomical observations were in full-bloom and they all saw nothing, and so, the phenomenon was a local one, no?  But, keep reading the Wiki article:

In The Evidence for Visions of the Virgin Mary Kevin McClure wrote that the crowd at Cova da Iria may have been expecting to see signs in the sun, since similar phenomena had been reported in the weeks leading up to the miracle. On this basis, he believes that the crowd saw what it wanted to see. McClure also stated that he had never seen such a collection of contradictory accounts of a case in any of the research that he had done in the previous ten years.[10]

According to theologian Lisa J. Schwebel, claims of the miracle present a number of difficulties. Schwebel states, "not only did not all those present not see the phenomenon, but also there are considerable inconsistencies among witnesses as to what they did see". Schwebel also observes that there is no authentic photo of the solar phenomena claimed, "despite the presence of hundreds of reporters and photographers at the field" and one photo often presented as authentic is actually "a solar eclipse in another part of the world taken sometime before 1917".[42]

And, so, perfectly natural explanations exist, and by Occam's Razor, we ought to go with those!  You might want to focus on the so-called "Miracle" of Calanda, but I have some responses for that one, also!