Thanks!
I initially was trying to apply the 26 detection policies and move the agent to a new server in one shot. This isn't working with any servers (the ones I'm trying to move are domain controllers).
I've withdrawn policies, tried moving the agent to the new server, then reapplied the policies in small batches and I recieve the same error right off the bat.
I tried moving the agent back to it's original policy group (and management server) and the error persists, even there.
Then, I tried applying the detection policies first, then moving the agent to a new management server.
It's the same exact set of policies, except one policy group points to manager A, and the other policy group points to manager B. For whatever reason, returning the agent to it's original policy group doesn't resolve the error.