I highly suggest a forum for the intégration with building system.
4.18 integration is better with your new video but my first try turned into nightmare… changing enum has shown in the first step of your tutorial doesnt ask to recompile some blueprint (no * displayed on blueprint)… ive stopped my try in the middle after fixing mesh rotation… i have error while in editor saying the no placement during trace is not able to get reference to master building reference.
It seems that the cost variable that you changed name created issue too… i had to reconnect lot of pin.
ive followed your step but its hard to rely on the tutorial when i dont get same result on screen.
i can send you an email with the email related to the account i use on ue4 marketplace so you can send me the project files already implemented.