Anyone have any idea why I would be unable to use the League client voice chat? (I'm on a Mac, using headset, discord works just fine?)

it doesnt work for multis

When you say can’t use, do you mean you can’t hear yourself talk? Do you have “Join voice channel” turned off cause if so then you need to manually hit “connect to voice chat” either in game or in party lobby.

Go to settings from your client into voice.

Sorry what do you mean?

No one can here in the league chat. I’ve autoconnected, manually connected, tried threshold and push to talk still nothing womp womp

I already told you... it's because you're a multi

wut is multi?

Are you in a party ?

You can't talk to people who aren't in your lobby or queued with you....

Yep in party queued together

Never heard of it not working but also never tried it in a Mac, contact riot via ticket.

check your settings first though make sure your proper device is set or see if you can set a different one.