A proposed solution to this has been given by the licensee, please see the related UDN.
Open any level in editor.
Duplicate the material in the image attached (from UDN)
Add a post process volume to the scene and set to "unbound". Assign the material to the PPV.
Start PIE
Open the console and enter:
r.DynamicRes.OperationMode 2
r.Test.DynamicResolutionHell 1
The PPV calculations will jitter and be incorrect.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-190372 in the post.