I had virtually the same thing happen to me on a road trip this weekend. Charged at 114 kW for about 5 mins, then amps dropped to about 60A and stayed there. Tried another stall, same deal except the amps fell almost immediately.
The issue was Range Mode: If you leave range mode turned on, the forced cooling fans do not run -- the car attempts to cool everything through the passive radiator, and that's not enough on a hot day. The charging rate will be limited due to high battery temperature.
The next day I turned range mode off and charged at the same supercharger and everything was fine.