i'm not sure what you want to do? First you have activated "Bullet" for platforms, what means the object is moveable, but on the other side you have set "Immovable" to "yes". If you don't want to use these object as "bullet", what I guess, I would recommend to disable this for platforms. And you need to give platforms the behavior "solid".
If you want to make the middle platform to allow jumpthrough just give it the behavior "Jumpthrough"
And give your player the "Platform"-behavior. Then it should work.