Why didn't the Resistance scan/search the Raddus for a tracker?

When Finn declares it "Impossible" for the fleet to have been tracked through hyperspace, Leia matter-of-factly responds, "Yes, it is. And they’ve done it.” But tracking has been possible since before ANH with a tracker planted on a ship. So why wouldn't the Resistance first start tearing the Raddus apart searching for one, instead of just assuming that the FO has somehow achieved a breakthrough technology previously thought to be only theoretically possible? What makes this especially confounding is that Leia is holding a hyperspace tracker in her hand. For all they know, Rey could have been intercepted by the FO and they could be tracking them that way.It seems strange that they make a really improbable guess that turns out to be true, and Poe bets the entire fleet on a plan even more improbable than the guess. The question of whether or not a tracking device had been placed on the Raddus could have given the mutiny storyline some weight. As it is, the characters seem to be rushing to get on with the story, but their actions don't make a lot of sense. If I commit a crime with a friend and the police come to arrest me with details only my friend would know, it's obvious that he squealed. I'm not going to assume that the police have developed the ability to time travel to the scene of the crime or read my guilty thoughts as I walk down the street. via /r/StarWars https://ift.tt/2BnQO4D