[whpalmer4]

They aren't. Blue items (by default) are members of single action lists, not parallel projects or action groups.

Parallel projects and single action lists are slightly different in behavior. A parallel project has only one next action (the first uncompleted action reading from the top, if it is available) whereas a single action list treats all available actions as next actions. The idea is that in a truly parallel project, you still only want one thing offered, but a single action list is just a container and so it doesn't presume the first one is any more important than the others.