Normally when a cause of death isn't released, it's because they are waiting on toxicology.
They called this a homicide though, so I think they likely do have a preliminary cause of death.
So it's possible they are waiting on tox to release the official cause of death, or maybe the coroner wants a second opinion or something.
They definitely don't want to screw this autopsy up with everyone watching. I bet they are getting several opinions. Didn't even think about the tox screens though! I'm sure they'll find some marijuana in her system.