So this is very weird, but the combination ⌘1 no longer works when I am logged into my iMac as me. It doesn't matter what app I have open (Finder, Slack, and Outlook all have different things bound to that combination, for instance); nothing happens when I press the combination. Both the ⌘ key and 1 work by themselves, but not together.

Specifically, if I fire up Key Codes and check the box to include modifier key events, I see the command key go down, but nothing when I then press 1. If I press ⌘2, I see the command key go down, the 2 key go down, then the keys come up. If I hit 1 by itself, I see the keydown and keyup events. But if command is held down, the 1 key triggers no events at all.

Now, if I log into the same machine as a different user, the problem goes away. So it's something weird in my user profile, but I don't know what.

I have tried swapping keyboards in the input menu, rebooting, killing every running application I could find... none of it helped.

So any tips appreciated..