See figure - I apply a rotation to the fixed rod through a master node of a rigid body constraint. The master node then has a rotation, which I should be able to look at for a reaction torque, but CCX does not output reaction torques.

There does not seem to be a simple way to get this information, or is there?

If you have defined/transformed your master node into a cylindrical coordinate system and added the torque as a boundary movement to the master node by a Radius, a radian angle, and Z in cylinder axis, your problem could be that the cylindrical coordinate system in ccx is more a tangential coordinate system than a cylindrical since a given node is moved the tangent distance and not the radial distance as normal expected in a cylindrical coordinate system

You should get some reaction moment output if you request displacements for the ROT NODE. It may just not work in 2D: Zero reaction moment when reading from ROT NODE in 2D

That did it. I asked ask for RF output at the ROT NODE, took that torque and loaded the master node, which matched the original deflection. Many thanks!