Classic Shell: Forum

The search sub-groups don't collapse (and therefore can't expand). Even by right clicking them and selecting 'collapse' (or 'expand') they don't collapse (and therefore can't expand, for they are already expanded).
It should also be noted that the header starts in the collapsed state (says 'expand' when you right click, arrow points right), while the content starts in the expanded state (it shows), and doesn't collapse (hide).

The collapsed/expanded states are not fully collapsed or fully expanded. When all categories are in collapsed state then the space is evenly distributed among them. If one category is expanded then it takes as much space as it needs and the space that's left is distributed among the rest.

Think of it as "normal" and "maximized" state.