There could be multiple reasons for the inability to recognize, you can try the following methods to resolve it:

1. Unplug and replug the receiver, try plugging it in both directions to avoid poor contact causing recognition issues;

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

3. Try connecting with a different phone to avoid issues caused by faulty cables;

4. If connecting to an iPhone, go to the phone settings to locate ’General‘→'About' and check if there is a wireless microphone driver. If not, the cable certification is missing and you need to replace the cable.