Thanks for posting this solution. I was trying out different editors to see which I preferred (Visual Studio community 2017 vs Visual Studio Code vs CLion) and through it all when I came back to VS2017 I had the same “Unable to start program…” message. I noticed the compile times were almost nothing, which I knew was wrong but due to my lack of experience with VS I didn’t know why. Through it all someplace along the way the UE4 project was bolded and set as the StartUp Project in the Solution Explorer. Your fix got me back on track!