I've been running through some tutorials to learn Houdini and I know this one's a little outdated,
but I ran into a problem at the end. After outputting the crumbling columns as a geometry sequence he brings it back in as a file sop and runs it through a material sop, where he is able to call on the group "inside," to mean the inside surfaces of the columns as they are breaking. For me, under the group menu, it just says "no entries."
After putting down a break sop before the material I did have the group "inside," but of course the break sop is not something I want in there.
Thanks for any input! File attached.