Unreal Engine 4.6 Preview!

Hi,
I feel really stupid for having to ask . How do you re-set the swarm agent to work with 4.6? Between upgrading to 4.6 from 4.5.1 and the latest Microsoft Tuesday event for Windows 7, I now get a message that says “Swarm agent failed to load” and the lighting build dies.

So is getting even stranger. While I get message, I can see that the swarm agent has in fact loaded but seems to have gone off into the exporting scene mode and never returns. On creating a new level, everything seems to work fine. So I am thinking that something must be wrong with my level. Where should I start looking?