We have tried to fix the issue in the current release. Please update Illustrator using Adobe Creative Cloud application to the latest build for version Illustrator CC 22.1.
Please refer to our knowledge base FAQ – https://illustrator.uservoice.com/knowledgebase/articles/1844590 if you face difficulty in the update.
Ashutosh Chaturvedi | Sr. Quality Engineering Manager – Illustrator
Adobe. Make It an Experience.
PS: We are only referring to the issue that got introduced in CC 2018. As I can see there were few workflows that were existing even in older releases. Please log a separate request for it so that we all can track it better
An error occurred while saving the commentColin Bright commented
I've had this one on previous versions. Figured out that it was the result of erasing a guide with the direct selection tool, which leaves the invisible "end point" in the document. If that guide was part of a group it can cause problems. Try clearing the guides.