Suddenly not receiving notification emails for purchased Smithsonian programs

As a regular attendee of Smithsonian  Resident Associate programs hosted via Zoom I had until the beginning of March 2022 been receiving notification emails with links to join said programs beginning about 2 weeks before each one. Since then, I have received no such emails, which, according to the Smithsonian, I had and should be still receiving directly from Zoom.  My email account is a plain personal Xfinity account, and I do not use personal filters to block or  divert incoming emails, nor have the expected notification emails been otherwise directed to a spam folder; they are simply not arriving in my inbox. I am at a loss as to how to correct this problem and any suggestions--especially ones that have been tried and worked in similar circumstances--would be much appreciated.