Images in the Render Layer nodes of the Compositor disappear Images in the Render Layer nodes of the compositor disappear each time a new layer is rendered. It only keeps the most recent rendered image. The other layer nodes are blank.

I've set up my scenes with layers correctly and the compositor setup is correct with the different layers. 
The rendered layers show in the Image Editor.
Compositing is checked in the Post Processing options.
Transparent option is checked.
RGBA is checked for alpha channels.

I've searched for answers but no luck. I've wasted too much time trying to solve this.
OK solved. I was manually rendering each layer and the compositor was only reading the last render, which was whatever layer I had just done. I let the compositor do the work and it handled it.