For some reason, when I mirror an assembly, and use same references, the mirrored parts do not end up across the mirror plane. Am I doing something wrong here?

I can see the "Source Products" and then it shows in blue highlight (to the right) what I intend to produce. It also shows in green the "Symmetric Products" that the tool ultimately produces. Not sure what I need to change to make this work correctly. 

Thank you for your help in advance.