Vegas Pro 15.0 Fade In/Out
Well... You could try to place the clip that you want to fade in/out on top of the other clips. If that does not work, you will have to split all of the clips at the same place and make them all fade in/out. If doing this will ruin the whole project video because you have other effects on it, then I suggest rendering the video without adding any fade in-/outs and then opening a new project and adding the video you made, then making it fade in/out wherever you would like to. I hope this helped!