I have two components with flat faces that I am trying to mate with Parallel. When I select them SW defaults to the tangent mate.

If I pre-select the Parallel button and select one of the faces I get "Select entity is not valid for current mate type".

Both of the components are imported STEP files.

Never had this problem before, I have performed this task dozens of times with similar components. I just upgraded to SW 2018.

Anyone know what is going on?