Jump thru not always works

I'm using Chrome 22.0.1229.94m, Windows 7 Ultimate Service Pack 1, and here are the specs: dl.dropbox.com/u/41571201/specs.PNG

I'm also not using third party plug-ins for C2 on this project.

I don't use the normal controls for moving the player, I use K to jump and the arrows to move, and to fall down a jump thru you have to press both down and K.

Problem is that this only works as long as the player is INSIDE or BELOW another object with jump thru behavior, I have this "stairs" that are essentially a large pile of blocks with Jump Thru behavior one over the other, and you can step on each one and fall of each one no problem, as long as it's not the top one

If you're standing on the top block, you wont be able to fall through it... any ideas as to why this is happening?

(This worked just fine before r109-111)

Here's an example of my problem:

dl.dropbox.com/u/41571201/JumpThruProblem.capx

Thanks in advance.

Should be fixed in the next build.