I just noticed that "Display test briefly" no longer works with KM 11.
However, "Display test in a window" and "Display text large" do work.
Seemst to be working fine on KM11 here. Are you certain your Mac is not set to 'Sleep' or 'Do Not Disturb' or any of those that hides notifications? (That is what my Mac is set to whenever I think this action is not doing it's thing.)
Thanks for pointing that out, but no, that's not the case. Well, a minor problem. This is certainly not the most important action. 
Maybe not, but you'd want it working. And weird that it works for some but not for you. Are you on Sonoma? I'm still on Ventura here.
Ah, the "engine". You are right. I was just looking at KM 
. sorry. Yes, now it works. Thank you both. 
4 Likes