Unable to model shockwaves in comsol

Hi all,

I have been attempting to model high speed flow over a cone, however for some reason I cannot get a shockwave to form. The attached image shows the pressure contours at an inlet speed of 2000 m/s, so far above Mach 1.
The atmospheric conditions I used correspond to about 61km altitude, so the pressure is only about 30 pascals however I don't think this is the issue.

Any help would be greatly appreciated!

Thanks,
Ben Brooks