RAM preview doesn't save when using multiprocessing

I'm running After Effects CC on a MacPro 2013. When I normally render a RAM preview, and I finish playing it, the green bar stays.

When I switch to the multiprocessing feature for RAM previews, after I finish playing it, the green bar disappears.

I have a large SSD global cache drive being used, so storage of the preview isn't the problem. There's plenty of RAM in the system (64GB). I've tried a number of different multiprocessing settings, and even if I only use 2 processors for RAM previews, they won't save after I play them.

Is this just the way RAM previews work with multiprocessing, or can I change some settings to fix it.

Thanks!

Jerry MacKay

Littleflick Pictures