Hey Rosemary,
Thanks for reaching out to us!
I’m sorry to hear that you’re having issues when using the Recurrence feature of our plugin. I did some testing as well and it looks like this is related to a known bug that we do have in the current versions of our plugin with the single date exclusion.
I’ve added this ticket to that thread and you’ll be notified here as we make progress on address this bug. I do apologize for the inconvenience this may cause.
In the meantime, you can remove the single instance by going to that date of the event on the front-end of the site while logged-in. From there, hover over the “Edit Event” button in the admin bar and select the “Break from series” option. Now, you should be able to delete that single instance without impacting all the other instances of the event within the series.
Let me know if this helps.
Thanks!