COLLADA mesh objects behave instable when stacked on top of each other
I am trying to simulate a simple assembly with a robot in gazebo (version 9.13.0). The objects are COLLADA meshes, rendered in blender, and are simple flat objects. When I try to spawn the world, where two of these objects are stacked on top of each other, they behave in a really instable way and bounce off each other. See video.
I tried setting max_vel to really low values and to 0, but that didn't solve the problem. Setting collide_without_contact flag is not an option, because I need the physical interaction behavior between the objects. Also when looking at the contact points in Gazebo, you see them flickering on and off. I'm assuming this is part of the problem that the contact points are not constant?
Is there a problem with my generated meshed or is this behavior inherent to using meshes in gazebo?