It is the troubleshooting video for the AM8 mic, but it can also be applied to the AM8T microphone.
Make sure the AM8T is the default input device of your PC and software.
Speak a little bit close to your mic capsule.
Test the mic with another USB cable and test the mic on another PC or Laptop.
Reinstall the mic driver (Only applicable for Windows)
How to Reinstall the AM8T:
Search and open the "Device Manager" in the search bar of Windows. Click the "Sound, video and game controllers", then choose the "FIFINE microphone". Click “Driver” and “Uninstall Driver”. Finally, plug your mic into the PC and install the driver again.