New Outlook won't let me add my outlook email account.

I'm having the exact same issue. I just made my new outlook.com email my primary alias for my Microsoft account. My previous primary alias was a gmail.com email. I was trying to experiment and see if I could get Microsoft To-Do integration if I signed in to New Outlook with the Microsoft account I was using for To-Do. But I had to change my primary alias to avoid Outlook confusing my Gmail account with my Microsoft account. But when I tried to sign in, I had the same issue as OP.

SOLVED! (hopefully) What you need to do is to click the switch to switch back to the old outlook, then add your account, then click the switch again to go back to the new outlook, and your account should be there. It said there was a problem with the account once I switched back, but I clicked on the icon to fix it, and it resolved itself. Hope this works for you.

Hello ShadeZinc,

Where's that switch?

I have a similar issue. When I add an Outlook.com account, it adds correctly. However, it does not show in my accounts list. When I try to add it again, it says that account already exists. I just need it to show in the acccounts list.

Should just be in the upper right-hand corner. If it's not, maybe you don't have the right version of Office, I don't really know.