I use hotmail.com with Firefox on a Win10 computer.
Like everyone else I get spam/phishing junk mail. I've reduced the volume significantly by blocking the entire domain whenever hotmail will allow, else I block the username@domain. Obviously, blocking "domain.com" blocks "email@example.com", "firstname.lastname@example.org", etc. I also report the spam by forwarding as appropriate . . . to paypal, amazon, facebook, etc. and to a couple of general spam-fighting addresses.
I've found it easiest to store all these spam-fighting addresses in a group in hotmail. That keeps me from having to remember all of them plus the "general" ones. Then when I forward, I simply remove any addresses that are not appropriate for that specific junk mail. I don't forward phishing that "appears" to be from Paypal to Amazon or Facebook, etc.
Before today, when I clicked on a group email, it showed in the address line with a "+" to the left of the group name. Clicking on that "+" would replace the group name with all the individual addresses. Then I could quickly remove inapplicable addresses.
But today, suddenly, the "+" no longer appears. I cannot see &/or remove individual addresses.
Have I inadvertently changed a setting? If so, how do I reset it?