We’re also struggling with this not being possible. When this will be implemented it would also be great to have a bit more control, for example in the tree setting you’ve got a setting to determine how many levels you want to expand. This would come in handy 

Could someone give an update concerning the implementation of this topic? 

Since the grouped columns are a powerful UX tool to group large sets of records. , we would also like to see the possibility to by default have all rows closed. Since more often than not, our users do not want to open the first record. 

This indeed sounds like a logical thing to have. We will need to add a setting to the SF for this. This could be as simple as a number indicating how many levels deep should be expanded.

@HarryA It might seem strange, but that is actually a bit more difficult, because Univeral really likes to have an active row and there are just a few cases were there isn't one, like while adding. And a collapsed node itself isn't a row.