I'm running 1.2.7 and I notice that the PAR files don't get selected to download when I do a collection. I thought there was a property setting for this, but I can't seem to find it now. I'd prefer downloading.
the rigthmost yellow rectangle "par2" button, just check it.
probably at a later point it will move towards the "pause par2" button, so it won't be strictly collection related, since it makes sense to apply it universally (given "select related headers").