Sorry to report that the iCloud solution does not fix the problem. If I create the event for a hour or so from now, I get a time to leave alert. If I create the event for further in the future, such as the next morning, I get no alert. This is consistent over my Mac, iPhone, iPad, and Apple Watch, so it is certainly not an iOS issue by itself. It seems to be tied up in the changes Apple made to Location Services across their platforms. It seems Calendar can't determine your location if it has not been accessed recently.
I found one possible clue in the preferences for Calendar on the Mac. Under Alerts is a check box to use Time to Leave (it should be checked). Under that box it says, "You will not receive alerts for events with destinations that take more than three hours to reach." So if Calendar can't access your current location it may assume you are farther than three hours away from your destination and forego the alert.