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,
Please accept my sincere apology for the inconvenience. Please get in touch with us at any of the other support channels – https://helpx.adobe.com/support.html . Since this is not a generic issue that we can reproduce at our end, we will need someone to look into your machine to figure out what is going on here.
An error occurred while saving the commentMatt commented
I'm having this exact same issue and it is a nightmare! Using MacOS Mojave, Illustrator v 23.0.1. The only fix is to quit Illustrator and then re-open. Illustrator also gives me a 'Crash Report' whenever this happens, even if the app seems to close correctly.