SOLVED!
The path to the script in the Boiler plate application is obsolete. This line in the index.html file must be replaced with the one pointing to download.uipath.com
<script src="https://uipathrobot.azureedge.net/Latest/UiPathRobot.js"></script> (Obsolete!)
<script src="https://download.uipath.com/js/1.2.1/UiPathRobot.js"></script> (Valid)