Unite, minus front, intersect and exclude all work fine. But once I'm alt+clicking (on unite, minus front, etc), nothing is happening. Like, my 2 grouped shapes just stay the same. For e.g. when I alt+click on Unite, it doesn't even give me the result that clicking on Unite alone would give me. Can anyone please help?
Option/Alt clicking a Pathfinder Panel button essentially removes the "expand" aspect of the operations.
In other words, the operations is still performed. However, nothing is expanded. So, you see your original shapes outlines. The interaction between these shapes should react as expected using the pathfinder operation.
You will still see the highlighted outlines of the original shapes.
But how/where the shapes interact will change.
The advantage of Option/Alt-clicking is that you can move things around and the operation is still "live".... Note below the interaction between the shape is a result of the Pathfinder operation...
After Option/Alt-clicking you can use
Object > Expand Appearance and you get the standard Pathfinder result...
This is true for most of the operations. (I haven't tested each and every one).
Unite gives the same result with or without the Option/Alt key. The only difference is that with Option/Alt the operation is "live", allowing you to move the objects independently if needed.