"Modeling of a 3D Inductor" - Cannot define output

Hello,

I'm currently following the "Modeling of a 3D Inductor" tutorial and have run into a strange issue. I cannot define an output for my magnetic field study as the guide directs me to. When I try to select a boundary, all options have (not applicable) written next to them. I'd like to select boundary 79 as my output (see screenshot attachment).

I've followed the instructions to a T thus far so I'm not sure what might be causing this issue or how I can resolve it.

Thanks for your kind assistance.

The model and tutorial document can be found on https://www.comsol.com/model/modeling-of-a-3d-inductor-10299