I think there's been a recent change in the way build orders are issued to cons.
For some reason, I am not sure which yet, I sometimes issue an order to build something and only one of my selected cons goes to build it. Right now it's happening with the campaign com and some masons selected. I issue to build a thresher and only the com builds. Why? If I have multiple cons of any kind (including commander) I always, always want all of them to build it. I cannot think of a single exception ever.
Why did this change?