Admin view
Being an admin and using it are two different things. An admin starts off seeing the app just like every other member: no Admin tab, and the admin pages won’t open. That way you always see what the group sees.
To use your admin powers, go to Your settings (your name, top right) and press Turn admin view on for an hour. You get the Admin tab and its pages for an hour, then they switch off by themselves, so nobody is left with admin on by accident. Press it again for another hour.
You’re still an admin either way, so if the admin pages are missing, this is the first thing to check.
Admin view changes nothing for anybody else. Any office you hold works as normal whether it’s on or off, because offices don’t come from being an admin.