It has not been mentioned yet so I'll ask - what keyboard are you using?

Before I upgraded my keyboard I had a similar issue where I couldnt use Shift + 4 (part of my AOE) when I was pressing any movement keys other than W. What you are experiencing is likely key ghosting, a phenomenon commonly associated with membrane keyboards or badly made mechanical keyboards where certain key combinations can't be pressed due to the keyboard circuit blocking itself with certain key presses.

TL;DR: There is a chance this is a mechanical issue of your keyboard.