Undo key combo does not work

I ran into problem last couple weeks: I am using Mac and upgraded to Mojave (10.14.1) 3 weeks ago. The keyboard to undue previous step (CMD + Z), does not work; it had worked without a problem when using High Sierra. I get this message below, but if I use menu command (under Edit) it works. Applies to both LibO 6.07 and 6.1.3.