I first though that the problem was particularly large documents, but after generating some megabytes of json and inserting into a test bucket and backing it up I abandoned this though. I then tried updating the server from 3.0.1 (1444) to 3.0.2(1630), but this didn’t change anything either.
The only thing I have gotten working is to create a new identical bucket, clone all docs from the original bucket to the new one and then backing that up. So it must be something wonky with that one bucket. Although when I do this cbbackup starts working, but chrome still crashes.
So I’m probably leaving this for now, but please post any findings anyone else might have.