This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.
If the static mesh has Mirrored UVs on channel 0 it will mess up the "Unwrap UVs for Render" functionality even when using a different channel for UVs that don't have mirrored UVs.
The mesh that is currently unwrapped by the Render to texture BP has black Faces that are upside down
All the faces are right side up when using UV channel 1
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-37700 in the post.