@Olivier Fischer - Can you be more specific, e.g., where exactly are you when you click this "+" symbol?

Better yet are screenshots - where this "+" symbol is and what happens after you use it. 

I just tried and now it works again. 

@Olivier Fischer - Interesting as I have only ever see this “+” symbol with the help text of Add teams:

Are you by chance on the Business or Enterprise Plan?

In the end, I’m glad to hear it’s working for you again!

It was enterprise plan. I didn’t do anything, but works as expected