There may be multiple reasons for not being recognized. You can try the following methods to resolve the issue:

1. Reinsert the receiver, trying both orientations to avoid poor contact causing recognition failure;

2. Uninstall and reinstall the HollyAudio APP to ensure the APP version is the latest;

3. Try connecting with a different phone to see if it can be recognized;

4. If connecting to an iPhone, go to the phone settings, find about the phone, and check if there is a wireless microphone driver. If not, it means the cable certification is lost, and the cable needs to be replaced.