Can't Copy and paste in Illustrator on macOS Catalina

You can have a look and see if this helps:

https://community.adobe.com/t5/Illustrator/macOS-10-15-Catalina-File-Open-Save-Issue-Addressed/td-p/10693849

There is no Illustrator officially compatible with macOS 10.15 at this time.
If you expect reliable operation, return to an OS that is guaranteed to work.

Hi Dorote,

Sorry to hear about the trouble you are facing with Illustrator. I would request if you can share a few more details like:

• Version of Illustrator.
• Is the issue related to a specific document? Try checking on a new document.
• Where the files are saved (Network Drive/ System HDD/ Shared Folder on System /External HDD)?

Regards

Rishabh