With the Abode Premiere Pro 2019 update the "undo" command (ctrl+z) does not work on changing values in Effects Controls. If I make an edit in the timeline, then change a value in the Effect Controls, for example make opacity 50%, when I use ctrl+z it undoes the edit in the timeline, not the effect change in Effect Controls. Using the Edit>Undo menu option does not work either. I've tried this on Motion, Opacity, Lumetri and third party effects, nothing works. I have Premiere 2018 still installed and I've confirmed ctrl+z still works properly with that version.
Mac OS 10.13.6 on Mac Pro (Mid 2012)
Can't replicate your issue on my 2013 iMac using Premiere Pro CC 2019.
Effects control changes are undone by using Command+Z correctly on my system.
Are you working with an updated project or with a new project created in V13?
You might want trash your preferences:
It's an existing project I updated. But I just came back to my computer after exporting some files and I can't replicate the problem. I'm not sure what caused it or what fixed it, I haven't deleted prefs. I just exported some sequences to Media Encoder to render, came back and switched back to Premiere and now it's working fine. I'll update this post if it happens again. Thanks.
(And yes it's Command+Z I was trying on my Mac, I have a PC too but I was not using Control+Z on the Mac .)