Check this out 4.8

https://docs.unrealengine.com/latest/INT/Support/Builds/ReleaseNotes/2015/4_8/index.html

I am showing you all this because the key focus here is how many bugs have been fixed with the unreal engine and also

Major Features

Improved Editor Stability and Quality of Life

This was a really big focus for Unreal Engine 4.8. With every Unreal Engine release we fix hundreds of bugs and add many new features, but with Unreal Engine 4.8 we've worked hard to improve editor and game stability, as well as to address many of the most common engine bugs and small feature requests. We hope that the result is a very solid engine runtime and editor, and we'll continue to make stability a big focus of future releases.

New: SteamVR/HTC Vive Support

Unreal Engine now has comprehensive support for Valve's SteamVR API and HTC Vive hardware!

This is why we have done a lot of work in 4.8 and we had a slight hickup, but like I said we should have the game converted to 4.8 from 4.6 in the next couple of days. Well worth the time and effort.