Can't apply thickness to mesh
I'm making my first forays into modeling clothes in Hexagon, and I've run into an interesting issue. I'm trying to use the method of adding thickness, then deleting all the inner faces, but when I try to apply thickness to my first totally from-scratch model... nothing happened. I've tested it with a cylinder (works fine) and another piece of clothing I made based on a starter template (also works fine) - in both those cases the thickness appears and I am able to edit the numbers, validate, etc. When I try it on the trousers I've been working on, Hex just highlights all the edges and vertices in blue. Changing the numbers on the thickness properties does nothing, and if I click on the lightning bolt, nothing happens. I can't seem to create thickness for this model.
Any idea what's going on? I'm guessing there's a problem with my mesh - and I don't really like how it's turned out, so I'll probably start over anyway - but I'd like to know what exactly is happening and what Hex is trying to tell me!