Box Collider z Axis unwanted reset

I have the same problem. It seems to work fine when I use certain sprite collections, but the problem returns when I use the collection I need to use, or when I use a newly created sprite collection. I tried to remove and reload the tk2d sprite component, and the collider component disappeared entirely. This seems to be some sort of Tk2d bug. Let me know if you make any headway.

I worked around it by creating a cube with and added the sprite as a child to it. Then disabled the mesh renderer for the cube to make it inivisble. There I added a rigid body and restricted the movement. Since the sprite is attached to the cube, it follows the restricted movement. Another odd thing I noticed regarding this issue is that when I have two objects add a box collider, set "IsTrigger" and add a rigid body, then the objects do not collide but fall through each other.

Thanks. I will try some creative object parenting, though I still find it very frustrating that I can't have both a sprite and a collider on the same object, especially since I had it working before doing the latest TK2D update.

As for the "IsTrigger" issue, that is an intended behavior. That option is for when you want a collider to not be a physics collider, but instead be just a trigger for game events. Useful for making waypoints, powerups and such.

In your sprite's collection, make sure Collider Type is set to "Unset"

Make sure that after you set the Collider type to "Unset", that you delete and re-add the box collider and rigid body to your sprite. That fixed it for me.