I recently redid the Twin Stick Tutorial to get back into Unreal, and to my dismay creating a new custom C++ class broke my project. It comes up with the error “Failed to compile target. Try manually rebuilding from Source file.” After some digging through the error log, I discovered the issue is UE4 likes the Windows 8.1 SDK and I only had the latest version, 10.1, installed. After downloading and installing the windows 8.1 SDK everything worked as expected. Since this is a beginner tutorial, I figured a quick answer should be somewhere on this forum.