Why don't the keyboard shortcuts to switch Terminal tabs work anymore?

I just got a new Mac with macOS Ventura. I use Terminal often, and several tabs in it. Why doesn't the keyboard shortcut for switching tabs work anymore?

I understand that, for some reason, it changed from command-1 (or command-2, or command-3, or so) to option-command-1 (-2, -3, etc). But they don't. Or, they'll work for a short while, and then stop --- sometimes for one particular tab, sometimes for several tabs, sometimes for all of them --- and nothing but quitting and restarting Terminal will bring it back.

Under Terminal/Settings/General I have checked, turned on, the 'Use command-1 through command-9 [sic] to switch tabs' option, which has no effect on this behavior.

What is broken here and how long has Apple been refusing to fix it?