Not sure if this is a bug report or a feature request. The Collapse function is inadequate.
When you right click in the Tree and select the Collapse function, yes it successfully collapses everything, but then if you open one item then anything inside that item that was expanded will re-expand. For example, if you open up a subassembly tree, and a component's feature tree, and it's Mates folder, and then you use the Collapse function to close it all, and then open that subassemly again, all of those sub-branches will pop open again.
The Collapse function seems to work only at the top level of the tree. It should recursively go down through all levels and collapse everything inside.