For example: One has two dolphin instances (i.e. windows) running which are in the same tab-group. The icon-only-taskmanager indicates a "application group". If the "group click action" is set to "Present windows effect" a click on the dolphin-group icon does nothing in this case. It should at least bring the window to the foreground (as is done when clicking on an ungrouped task-icon). If there are at least two tab-groups the effect is working as expected. (So to reproduce this one really needs exactly one tab-group).

Reproducible: Always

Steps to Reproduce:
0. set up icon-only-taskmanager with "Present Windows effect" as "Group click action"
1. open e.g. dolphin twice
2. tab-group those two dolphin windows
3. click on the dolphin-group-indicator in the icon-taskbar.
Actual Results:  
nothing happens

Expected Results:  
the tabbed dolphin window should at least get to the foreground.