Hi iGamersBox
I'm not sure the full settings that you use on your game so I did it on my way, at least it answered the main question why the planet don't get recognice, I hope it helps.
Capx: https://www.dropbox.com/s/am8oj6q2mj1sdbr/GravityPlanets.capx?dl=0
The problem you had in your example is that you had an
Every thick: set the player angle to the planet, but you don't specify wich one so C2 will always pick the first planet, So when you change the planets as you don't specify on wich planet you are in C2 will always pick the first planet every time.
So what I done is, create an instance variable "PlanetGrab" to the Indicator objects and I linked Each one of them to their Planets UID, I done this manually but you can do it in auto mode if you like,
Then I create an instance Bolean: "Is Active" to the planets so the player can trigger on wich planet is currently in