Ableton to Discord, through BlackHole, not outputting audio

[LilacPeregrine]

I am attempting to route audio from my external microphone, through Ableton, then out and to discord.
By setting Ableton to input audio, I can see the spectrum, so that is working.
The output is set to Aggregate Device.
Aggregate Device has:
Macbook pro speakers (muted)
BlackHole (16ch)
and External Headphones.

Discord input is set to the same Aggregate device, yet no audio comes out.

I have tried these so far:
Setting the aggregate device as "device sound output" does not seem to change it.
exporting the audio through BlackHole purely, and not through aggregate device, did not seem to work either.
If the aggregate device has the microphone, then it is only the unfiltered audio that discord receives - so discord can receive audio from the aggregate device.

I believe that somehow, the channel that Ableton is outputting is not the same that discord is listening for, but I do not know how to change that.

Any help is appreciated - thanks!