- When I configure a format with grouped list mode (by type in this case, groups folded), after opening a lister with the format - you cannot open any groups:
- Similarly, when I display the lister with expanded groups (using DO commands to switch to some other view and back to list), there is no way to fold the groups.
- I also see, that in expanded grouped list mode the display format imitates Explorer, which is pretty much misdesigned - items should flow as in list mode without grouping, with next group following the previous in the same column, not start a new column.
The horizontal scrolling modes (list and tiles) don't currently support collapsible groups. You could switch to Small Icons mode which is basically the same as list mode other than it scrolls vertically.
Pity. These modes cloud surely use grouping 
Maybe it could be possible to add to Small icons mode a setting to arrange items in columns, not in rows?
That would turn it into list mode, and one of those is already too much 
We've made a change for the next version which ensures groups don't get (or stay) collapsed when in the two modes (List and Tiles+Vertical Layout) which don't support it.
(This was already done in most cases, but there were two where it had been missed.)