要解决Android蓝牙发现广播接收器不起作用的问题，可以按照以下步骤进行：

1. 确保已经在AndroidManifest.xml文件中声明了相应的权限和服务，以及注册了蓝牙发现广播接收器。

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2. 创建一个扩展BroadcastReceiver的类来处理蓝牙广播事件。

public class MyBroadcastReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
            // 蓝牙发现开始
        } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
            // 蓝牙发现结束
        } else if (BluetoothDevice.ACTION_FOUND.equals(action)) {
            // 发现蓝牙设备
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            // 处理蓝牙设备
        }
    }
}

3. 在需要启动蓝牙发现的地方，注册BroadcastReceiver并启动蓝牙发现。

MyBroadcastReceiver receiver = new MyBroadcastReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
filter.addAction(BluetoothDevice.ACTION_FOUND);
registerReceiver(receiver, filter);

BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
bluetoothAdapter.startDiscovery();

注意：确保已经打开了蓝牙权限和BLUETOOTH_ADMIN权限，并且蓝牙设备是可用的。