sometimes the perspective of the reader and the character are quite different but i think the characters are dolts for puzzling over it for so long if it is just emrakul

To be fair, outside of say Sorin, no other character really has any idea that this new issue could be Eldrazi related. By the time Jace got to Zendikar, Emrakul had already left. Liliana has no clue and neither does Arlinn, they just both know that weird **** is going down and they need to be ready for it. Tamiyo knows a lot of things, but doesn't know about the Eldrazi in general, so she's missing a value peace of the puzzle.

In the end Sorin has that valuable puzzle piece and also knows that Nahiri has motive and skill to lure an Eldrazi titan to Innistrad. What he didn't know was that she was loose from the Helvault and wrecking things until recently. He's been busy off-world dealing with all manner of other issues.

Also none of the plane-bound population has any concept or idea of what an Eldrazi is, so none of the legendary characters would be able to sort this mystery out.

Jace was at least aware that there was a third Eldrazi out there somewhere, but in his defense, he was literally going insane throughout his investigation.

Also Jace wasn't on Innistrad to look for Eldrazi. He was there to find Sorin and bring him back to Zendikar, per Ugin's orders (though how Ugin expected Jace to muscle Sorin back to Zendikar is beyond me). Once he got there, he got caught up in the general weirdness of the plane and stumbled on a mystery that needed solving (by him...totally). Then the madness set in.

But over all, Jace had/has no reason to believe that there is an Eldrazi titan behind all of this. For all he knows, he just stumbled into H.P Lovceraft world and this kind of thing happens all the time here.

Oh, also: Get your SOI Magic Story eBook Collection while it's hot!

Maybe Ugin sent Jace to strongarm Sorin with the intent of having Jace killed by Sorin?

We can only hope.

Yeah but if the mystery is only a mystery for the characters and not for the reader then I would consider that a failure. I wouldn't even call the story a mystery at that point but a suspense thriller because you don't have to actually figure anything out just wait to see how the characters react to the big horrible thing you know is coming.

Remember. They came as as as.

I can just see Jace turning back up and Ugin just losing his ****.
"what are you doing here?! I sent you to die! Can't you follow any damned instruction I give you you stupid biped?!"

Jace is a one-man sylex.

I'm fine with Ugin being the source of the strange bad stuff plaguing Innistrad of late, but I'm hoping for some kind of twist too.
Remember they came as
Remember they came as
Remember they came as

what does ugin have to do with it?

Ugin Emrakul

Honestly, I am at the point that if it isn't Emrakul then we are just going to have to deal with every damn set tons of screaming nerds "WHERE IS EMRAKUL RABBLE RABBLE RABBLE" Until she -DOES- show up.

Best to just kill her off now and move forward before the plot holes of Zendikar's story start seeping into other places. It is like... some kind of world eating threat.

GOOD GOD I FIGURED IT OUT. ELDRAZI EAT PLANES BY CREATING PLOT HOLES.

It would be amazing if eldrazi warped planes with plot holes and retcons, but wotc isn't that ballsy.

If proper plotting is reliant on consistent logical, then a being that warps reality...

That's exactly where I stand, too. I hope the entire eldrazi arc is going to be wrapped up as soon as possible. They should just imprison Emmy on the moon, then Sorin kills Nahiri and we can move on to something new that isn't infested with retcons. Maybe in the next block when we're going to Kalad- okay, nevermind, the retcons are here to stay.

Other than Chandra's story, is there anything involved with Kaladesh that is a retcon?

No, but some people have taken a rather staunch all or nothing campaign about the matter.