I was also facing same issue on unreal engine 4.15. After doing some research I found this was a bug at Unreal engine side and was reported by community. It has been solved in 4.16 release build.
I was also facing same issue on unreal engine 4.15. After doing some research I found this was a bug at Unreal engine side and was reported by community. It has been solved in 4.16 release build.