aggregate device not working as expected

I am using OSX El Capitan (10.11.3).

I have created an aggregate audio device within OSX’s “audio midi setup” and that device shows a signal as expected from BOTH 2 usb microphones connected to my Macbook pro when testing in audio preferences > sound and selecting the aggregate device. Tapping both mics with my finger register an equal input level.

However, within audacity, even though I have selected the aggregate device from the input dropdown (above the multitrack), audacity still only registers sound coming through ONE of the mics, not both.

Has anyone else run into this? Thank you

I don’t see how to edit the post, so I will reply.

Worth noting, the aggregate device works as expected when doing a recording from Quicktime via file > new audio recording. Thanks.

If the devices register in Audio Devices setup as “2 channel” devices, then the aggregate device will have 4 channels. This happens on my machine with El Capitan.
The monitors in Audacity only monitor the first 2 channels. Channels 3 and 4 do not show on the recording meter.
To record all 4 channels, set the number of recording channels to 4 in the device toolbar.