Can you try upgrading to the latest DayPilot Pro version?
Try running the following command in the console:
npm install https://npm.daypilot.org/daypilot-pro-angular/trial/2018.1.3156.tar.gz --save
Most likely, the tutorial includes a reference to a previous version of DayPilot that had a similar bug. It will be updated soon.
Let me know if it didn't help.