Currently it seems that stl format is not supported by Isaac Sim app. Is there any work around to still be able to do it?
Could you clarify whether you are referring to Isaac Sim Unity or Isaac Sim Omniverse?
I also had a problem when trying to import URDF files in Isaac Sim where the collision files were in stl format. Apparently it is not supported, I had to covert them to .obj using Meshlab.