I keep having issues with boundaries when using a 3D sketch and converted entities. I tried following my professors tutorial and I keep having this issue. Not sure where the problem is coming from or why I keep having it.

I select two curves, and I have no problem, then when I select the final curve, which is a projected sketch, the boundary preview disappears. 

I've done this 6 times from scratch now, several times, doing what the tutorial states, as well as just winging it on my own following the same process, yet I keep getting the same end result.