Thanks for the information provided to the Illustrator team.
We are able to reproduce this issue at our end and the engineering team is currently isolating this issue further to get to the root cause.
With Best Regards,
An error occurred while saving the commentNancy commented
Same thing has been happening to me since I updated my OS to Mojave. I tried restarting my computer, signing in and out of Adobe CC, closing my web browser, and resetting my preferences for Illustrator.
Finally found out what was causing the problem – Webroot SecureAnywhere.
If you look at your menu bar (the bar that runs across the top of your screen), you'll see a little green icon with a W inside of it. Click that icon and then click "Pause Secure Keyboard Entry". That should fix it right away. You'll have to click it again every time you shut down or restart your computer (I haven't figured out how to set it permanently yet). Hope that helps!