It's not a bug in hammer, you are doing something you shouldn't do. A sphere is the worst shape you can make in hammer, and hollowing it out is just not going to work.

How would one go about making a sphere without, well, making a sphere?

Ooh, yeah. I try to never hollow out a sphere. Here's some tips if you deem you must:

The fewer sides, the better.

The bigger the sphere, the better the chance that it will work. And I mean really really big. But not enormous. Like maybe the size of 2-3 elephants.

Reloading the map file will usually tell you if it worked. Sometimes the sphere is missing faces, or stretched strangely when you close and reopen the file.

If by some change you do get a good working sphere, be warned that doing anything at all to it, like moving it for instance, may make it 'break'.

If I need a small hollow sphere for a map, I make a pretty huge sphere with few sides, hollow it, scale it smaller, making sure that all sides are the same size, then make each brush face a detail.

I once got a beach-ball sized 12 side sphere to work as a func_physbox, textured it with that moving star field-type texture and put a solid black sphere inside it. It was a pretty cool ball thingy.

Good luck.

If you want to use a sphere, a model is much better. Spheres made in hammer just don't look or move correctly.

I see. Thanks.

Crazy is right, it's sorta like dividing by zero

Yeh i agree with Crazpip , spheres are best made as models

OFFTOPIC: Isn't bad wolf from docter who?

Take a look at this to learn how to make domes using displacements. Just a heads up, all of the domes you see in CS:S are models.

Word of advise....dont hollow a sphere....its not the best of idea's