Sorry if I’m misunderstanding the issue or if you already solved it, but I think UE4 is “hot reloading.”
There’s an option to turn off auto-compiling (which I think automatically launches VS) under Editor Preferences -> General -> Miscellaneous -> Hot Reload -> “Automatically Compile Newly Added C++ Classes.”
Of course, if your issue is that you need the auto-compile then this clearly won’t work because there doesn’t seem to be any way to auto-compile and not launch VS (which sure does look like an issue to me).
Hope I’m not just repeating what you already know!