I think this is an edge case.
- Create an instrument track with a kick and a snare (Impact XT).
- Add a pattern to it using kick and snare.
- In the Impact XT route the snare to a separate mixer channel.
- Now there are two mixer channels and one track.
- Right click on the track and choose "Pack Folder".
- Create a bus channel for kick and snare.
- In the drop down on the folder for the track choose the created bus as group.
- In the console click the wrench and choose "link expand/collapse of folder tracks with show/hide".
- When you now click on the folder icon of the bus, the mixer channel for the snare remains visible.
I think the intended behavior should be that the snare channel closes too, as it is linked to the track of the kick: it's in the same pattern, it uses the same instrument and most importantly it is routed to the same bus. Would be awesome if this could be fixed. :-)