Multiple Bus shortcut suddenly not operational

I use the shortcut (shift+alt/option+ left click) and (shift + left click) to route multiple outputs often, and it suddenly stopped working. It’s not a dead key because all of my other shortcuts using those keys are fine. Am I missing something really obvious? Did I accidentally turn on a feature that I’m not aware of? Where can I reconfigure this shortcut key command? I looked in the list but couldn’t find the specific function/key command combo. please help!