How do I fix this jump thru behavior

I've been trying to use this jump thru behavior for my game but found this glitch where my player falls through once they place the box on top of another box with jump thru on it. Sometimes my player falls through it while walking on top of it,

https://cdn.discordapp.com/attachments/816017874078007328/879828917765165086/UDJCjGkakg.gif

Is there a way to fix this glitch?

Hard to work out the problem without seeing the capx. Try recreate in a simple capx and repost.