The amount of time wasted before realising how to do this simple thing isn’t worth thinking about, but luckily it’s very easy in SCCM to search in all subfolders and it can be done by doing the following –

1. Navigate to any asset that contains a search bar at the top.
2. Select the Search Bar to ensure that the Search toolbar menu appears.
3. In the Search menu, select “All Subfolders” as shown below, this will search the current node and all subfolders.