Collision mesh not moving with static mesh

Dear all,
I have a physics enabled body to which I have attached a thigh, shin and foot. Attachment is by socket.

Thigh attaches to socket on body.

shin attaches to socket on thigh (the shin in the images is in red)

foot attaches to socket on shin

When I rotate the thigh relative to parent, the thigh collides with the ground but the shin and foot do not.
pxvis collision shows that their collision meshes are being left behind in their original positions and do not move. These images hopefully make it clear what I mean:-

The first image is simply the starting position. The second image shows the thigh having rotated and you can see the collision meshes for the shin and foot have not moved. The thigh is pushing up the body but the shin and foot just go through the floor.

Reported as bug UE-74654 - But maybe I am making a stupid mistake?
small sample project (just press play) can be downloaded from

Any comments would be welcome. I have tried what I can in blueprints. If I ‘wiggle’ the shin or foot then their collision mesh corrects to their current static mesh position. I can make this extra wiggle so small that you do not notice it and it all appears to work but it is hellish messy and just not right.

Any thoughts? I am quite happy to implement a C++ solution or experimental solution. Anyone know what function call(s) will trigger the movement of the collision mesh? Any small clue is appreciated.


Hi, its difficult to follow the issue. But i also had similar issues. My mistake was always the same. I enabled physics on attached objects. The solution was just to give the root object physics and all the other objects just have collision enabled without physics. Maybe that drives you in the right direction.