Thanks for the reply MichaelB2019.
Yes, I can see the email address in my contacts. It is my work email address, and often I will also duplicate my personal appts to my work calendar so that I avoid any conflicts between the two. I also have an additional 4 email addresses listed for me in Contacts. All of those auto-fill properly when I start to type any of them, as well as any other of my hundreds of contacts.
Currently, as I type the address, Calendar does not auto-fill this address, regardless of how many letters I type. I checked the link you provided. I'm all good there too.
This was working totally fine. However, I initially typed part of the address wrong when I entered it for the first time. Then, I entered correctly. So, anytime I started to type this address, both the correct and incorrect addresses would appear as options to select. I went to remove the incorrect one from auto-filling and accidentally removed the correct one. I then removed the incorrect one. At this time, I cannot remember what actions I took to remove these from auto-fill. I believe my removing the email from auto-filling is what caused the problem, as it is the only one I have an issue with, however I cannot figure out how to restore the functionality for this specific email address.