If a Calendar event has a location associated with it, no invitations are ever sent to any of the invitees. In fact, once a location is added to an event, no subsequent updates about changes to the event are ever sent to any invitees (including the addition of the location).
This failure is silent. No warning is given, the invitees are simply never informed of the event at all. This happens regardless of whether the invitees have iCloud addresses or not (in most cases, for me, all invitees are iCloud users).
I con reproduce this 100% of the time on both macOS and iOS. This error suddenly appeared recently, and since then I've learned from several friends that they have experienced the same problem.
How do I send invitations to events with locations from Calendar?