Hello frostymm,
I’m not sure what fixes you may of found, but have you tried deleting your Intermediates and Binaries folders, re-generating your project files by right-clicking the .uproject file, compiling, and attempting to launch?
If that doesn’t work, could you post all of the errors that you get when creating a new blank C++ project? Does it require adding a new C++ class to get these errors? If so, what kind of C++ class are you adding?