Both @csells and I saw an instance where a multi-line text field (I was using the one in the Gallery app's Material Text fields demo) stopped responding to some keyboard editing commands.

Both the up/down arrows and the command-A/command-C commands don't work. The left/right arrows did still work.

I had it happen once, and thereafter when I launched the app, I couldn't make it happen again.

I tried holding down keys when I started the app, running in debugger, debug mode, and release mode, and after the one time (which was in debug mode, but not in a debugger) I couldn't get it to happen again.

Chris says he couldn't get it NOT to happen for his app.