folders tracks collapses no problem, the folder on the bus channel only packs one channel away?

I am new to studio one and in the process of setting up templates that suit my workflow however I am having trouble with the track folders when I link them to busses, on the bus channel in the mixer when i click the folder button only one of the tracks on the bus goes into the folder.
I am sure there mus be a step I am missing or something in the setting causing this.  
any help with this would be much appreciated
thanks
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