Recieved 'Could not load file or assembly 'System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1

Would encourage others to raise support tickets, to help MS know something's wrong at their end.

I received a response which asks me to update the dll (obviously can't do that).

Or switch to using a gateway (I really do not want to build a pet server to link two cloud services together).

If you do raise a ticket, it might be worth mentioning these two options are not viable, to save a pro-forma response.

They've offered a teams call - will report back if any updates.