Mail.app doesn't show server settings
I have run into a very strange problem in Mail.app on my Macintosh (Mojave 10.14.6).
One of my email accounts stopped synchronizing. It is a Gmail account. I went into my account preferences to check the settings and update them if necessary, and lo and behold, the Server Settings didn't show any options for incoming mail and it was missing most of the options for outgoing mail settings. Yikes! See screen shot below.
Does anyone know how to fix this? I also checked the Internet Account panel in System Preferences and there were no options I could change for this account there, either.
As a last resort I can delete the account and add it back again but I would rather not do that if it can be avoided.
Thanks in advance for any help.
MacBook Pro 15", OS X 10.11