Macbook pro not detecting (recognizing) external microphone

I had a strange problem on my MBP late 2015 (running Catalina 10.15.7) with a Rode Mic and a TRRS adapter.

Everything was perfectly fine and during a live transmission the mic went dead. I had to quickly switch to my AirPods (awful sound compared to a external mic) to complete the transmission.

After the live event, I tried to troubleshoot the problem and found out the computer would not recognize it anymore. In the sound properties, it would not show up as input device, although a simple wired headset (similar to those that come with the iPhone) would be recognized as input "external microphone").

I tried ALL possible solutions documented on the web and Apple Support pages. MBP would just not recognize it anymore on the Sound properties.

I tried SMC reset, NVRAM reset, upgrade to last patch (I was one patch behind), upgrade to Big Ser (new OS).. nothing.

I decided to reinstall and restore from Time Machine, since I didn't have interest in running Bigsur yet. Voilà!!! Worked!

It seems the reinstall + Time Machine restore fixed something that was corrupted in the OS.

The problem is fixed now, but since all the threads in this forum about this kind of problem were closed, I decided to open this new one to document what was found.

Cheers!