Apologies for the inconvenience caused to you due to this issue.
Unfortunately we are not able to reproduce this issue. Could you kindly provide the following information to help us nail this down.
1)Kindly try the below workaround and let us know if that helps with the issue:
Kindly rename your Preferences folder placed in below location and share this folder with us in a zip file.
MAC: /Users//Library/Preferences/Adobe Illustrator 24 Settings//
WIN: C:\Users\\AppData\Roaming\Adobe\Adobe Illustrator 24 Settings\
Kindly share the above with us in a Zip file at ShareWithAI@adobe.com
Please mention the title of this issue as the subject of the mail.
An error occurred while saving the commentMichelle commented
I followed Hans' suggestion (from October 24, 2019.) I closed Illustrator and reopened it. From the home page--before opening or starting a new file--I went to Workspace and selected Essentials Classic and it magically displayed that workspace. I tested this with other workspaces, including saved custom workspaces, but nothing else worked, only Essentials Classic.
I opened a new file, saved it, and closed Illustrator. When I opened that file back up the workspace was still there. Now to see if I can create a custom workspace but for now I appreciate this workaround! Thanks Hans!