Download the licensee repro from here - [Link Removed]
Visualise Lumen surface cache (e.g. r.Lumen.Visualize 4)
Standard Scene (right hand box):
Packed Level Actor (left hand box):
Should also be visible in the scene that the reflections are incorrect as a result.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-174897 in the post.