Emoji keyboard won't appear on my MacBook Pro M3

MacBook Pro, M3, MacOS 15.2

When I hit Cmd-Ctrl-Space or Fn-E, the emoji keyboard should appear, but it doesn't. I've noted that in the Activity Monitor, the 'Emoji & Symbols' app appears and when I kill it and try again, it still doesn't work. The only solution is to reboot. This occurs now and then, not all the time and sometimes from the start of a (cold) boot. But rebooting is frustrating!

[Re-Titled by Moderator]