I'm rotation an object 90 degrees and back, and at each step I call octree.rebuild(). It's adding nodes correctly (as far as I can tell), but it rarely removes old nodes. So when it gets back to it's original orientation the octree is a mess.
This problem doesn't occur when the face count is very low. It works fine for a model with 14 faces, but the problem occurs with 519 faces.
My system is not very powerful, so it might not occur with this low face count for other people.
Starting octree:

Ending octree (after rotate 90 and back):
