When Yam Display is running with USB connected but still in ‘Wait for connection’ state, follow these steps. Try again after each step:

1. Restart Yam Display on your iPad/iPhone (running in the background).
2. Unplug USB cable and plug in again.
3. Check if your device is recognized by iTunes. If not, please check out this guide.

For some cases macOS Sierra does not recognize connected devices after reboot. Reconnecting USB cable may solve this issue.