The egg model has already been read and vertices collected from it at the time when the assert is raised. So this is not the problem. Still, the NxMeshDesc created from these vertices seems to be invalid. Thi sis checked before attempting to cook the mesh.
One idea would be that the mesh contains more than 256 vertices. Convex meshes are restricted to a max of 256 vertices.
If this is not the problem I would like to see the egg or bam file. Maybe I can figure out what is going wrong with this mesh.
enn0x