Hi there Don,
Thanks for reaching out to us on this, and sorry to hear about the issue.
I see you are a long-time licence holder, does this started to happen now or is it an ongoing issue? It would be great if you could share your system information with me so I can check if everything looks right on that end. Also a screenshot of the recurrence setup in the back-end will be nice to have.
Are you able to reach the server error log and see if there are any PHP errors in there? Do you have a local copy of the site or a staging/dev environment where you can test for this as well?
Please let me know about it,
Best,
Nico