See what is the right settings for outlook for spectrum email - Microsoft Community where the interim work arounds, until outlook (new) store app gets an updated pushed that fixes this, are . . .
a) if you can revert store app install from outlook (new) to outlook [ (classic) ] or mail app that ran separate from calendar app
b) configure outlook (new) store app using pop3 tls/995 instead of imap tls/993 same incoming mail server
c) use spectrum web app mail solution https://mail3.spectrum.net/ or alternative mail app in store supporting imap/smtp connections
You can revert back, but this is a forced update and Microsoft will just force it on you again. I already tried that.
I had the update, reverted back and it was forced on me again.