Lectures management: Search field not working

In the lectures management --> Tab "Absences" / "Notice of absence" / "Appeals" the search field does not do anything. It should be possible to search for the following data:

• Name of user, coach
• Course: Title, External reference / ID
• other if useful

Also it is not exactly clear, what one can search for. Add the tooltip question mark bomb with adapted text analog to the tab "Lectures".