It's possible I've botched something.
Nope, nothing you have done. I tried this running 2016.2b on the Mac too, and sparkles don't show up. Opened the the same test sequence under 4.3.2b and the sparkles are there.
My suggestion is to run 4.3.2b until the recent issues with 2016.1 & .2 are resolved. There's a reason why Sean pulled the most recent versions.
I've noticed issues myself with models not showing up under the layout tab with 2016.2b, but they show up under 4.3.2b.