MacBook will not recognize my external microphone unless it is already plugged in when it boots up.

DiPatrick wrote:

I have a 2019 MacBook pro running BigSur 11.6 and an Audio-Technica ATR2100x-USB external mic. The computer does not recognize the mic AT ALL when I plug it in via USB-C. However, if I shut the computer down, plug the microphone in and then start the computer up, the microphone is recognized. In this situation, if I then unplug the mic and plug it back in, it will not be recognized.

I genuinely have no idea what this means. Please help.

Sounds like a bug—

You can file a bug report using this same link: Apple Feedback http://www.apple.com/feedback

The best you can do is verify your macOS software is up to date,

verify your —Audio-Technica ATR2100x-USB external mic driver software is up to date or search Support/Help/FAQ/known issues/compatibility for your third party product:

How Do I Set Up My Audio-Technica USB Microphone with My ...

You can try—

resetting the SMC https://support.apple.com/en-us/HT201295

resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

(get at least two-three rounds of the chimes when holding the NRAM Reset)