Small object do not respect colliders?

[paaabl0]

I noticed unexpected effect: For two Rigid Bodies with Collider, the collision is not respected when one object is getting smaller (in my case 0.015m x 0.015m x 0.01m). I tried setting mas explicetely, density of the material and few other settings - the effect seems to depend only on the volumen of object.
Here is the example: there two simple cubes, joined with a fixed joint. All settings are default. No error at the simulation Console.

Bigger cube:

Smaller cube:

The smallest cube - object is ‘sinking’:

The only difference is the size of the cube. All object have Rig

Configuration is very simple and using default settings:

What might be the reason? Is there some configuration? Or material settings (e.g. small object are being ‘crushed’)?
Is there some limitation of the simultator in terms of the volumetric sizes?

According to isaac-sim-conventions this is cube 1.5x1.5x1cm

[AlesBorovicka]

Hi,
for small sizes its recommended to increase the simulation frequency, you can set it on a PhysicsScene - Num steps per second.
However the most likely cause here is the autocomputed mass, the mass is computed based on the volume so the mass difference here would be enormous.
I would recommend to add MassAPI to your rigid bodies and set some sensible values.
Here is an example I was playing with
cubeFixedSmallCube.usd (13.0 KB)

The autocomputed mass works in many cases, but unfortunately if you try to joint objects with huge mass difference the simulation quality is not great and the autocomputed masses will produce really big difference here.

regards,
Ales