On Demand Webinar not sending out recording links when registration received

[Amy71]

We hosted a webinar in April, and after reviewing the recording, decided we wanted to make the recording available as well.   After reading zoom support articles, it seemed that the best way would be to make the pre-existing webinar (now in the past) on demand, which seems to promise that anyone who registers for the now passed webinar would receive the recording link.  

I made the previous webinar on-demand, and set up registration for the recording.  However, a test reveals that nothing happened upon registration for the webinar.  In other words, no recording link was automatically sent to the registrant?  

Is it not possible to make a webinar on-demand after the fact?  If that is not the problem, does anyone have an idea why this isn't working?