I have a few more things to check. Could you try turning your any anti-virus software off and see if that helps? Also, I know you tried running it UE4 as administrator, but could you try running your own SwarmAgent as administrator as well to ensure that it can have the correct privilege? If neither of those things work could you upload your agent log from the swam agent.
Also just to check, you’re not attempting to use a swarm cluster at this point are you? Just a simple agent locally on your machine?