Hello LogicDesign,
You have in fact found a bug! Thanks for taking the time to report the issue, as this same set up does not occur in the 4.11.2 engine version. The good news is I have a simple workaround for you to use in the meantime. Simply disable ‘Motion Blur’ within your post process volume by setting it’s value(s) to 0.0 and you should be good.
For tracking purposes, the bug report entered is UE-32331. Once the issue has been addressed by our engineers, the fix will be added to the release notes for fixed issues within an upcoming full engine or hotfix release.
Let me know if you have further questions or need additional assistance.
Cheers,