Only juubi jins can react to ftg.

[Great Master Minato]

Dafuq. :|

Naruto and Mito were the only people with negative emotion sensing; "danger" sensing.

Why didn't Madara sense BZ?

Plot?

Forget It,It Seems I Was Wrong.

 

[Lightbringer]

All Shinobis Can Sense Danger...Minato Is A Kage...It's Impossible To Perform A Silent Kill On Him.
Konan Noticed Obito Was Behind Him But It's Was Too Late & She Couldn't Escape While Minato Can With His Instant S/T.
Like KG65 Said If Izanagi Was Going To Work Obito Would've Used It.

Obito at 14 only had 1 sharingan. I'm not arguing for his sake, I'm arguing for current Obito, who has developed as a shinobi and has a ton of sharingan spares.

 

[NarutoKage2]

But how would he sense Obito approaching if he has his sensing abilities turned off? If Obito attacks him while he's unsuspecting, then he will get hit.

You're making it seem like there's no possible way for Minato to get hit.

The scenario is.

1. Obito uses Izanagi and Minato thinks he won.

2. Minato lets his guard down because he thinks he's won, Obito's body is still in front of him

3. Obito quietly comes from behind and stabs him without warning.

Almost the same scenario that happened with Konan.

Except that Minato has his ftg mark on the REAL obito, and it was stated that the marking is a jutsu type that alerts him when it flies(moves, in this case obitos movement)

-The ftg marking was said to never vanish
-Obito was marked with his real body
-Even if he used izanagi, the instant he moves behind Minato he gets sensed/detected
-Hiraishin ensues

Adult ms obito loses the same way 'kid' ms obito did.

 

[WalksInShadows]

Madara reacting only to Tobirama's attempt at attacking him is pretty debatable since for starters, he knew how Tobirama was going to approach him. Coupled with the fact that Bee had Minato dead to rights in a similar situation, it hardly takes a JJ to be able to react.