Operating System: Windows 11 Home, Version 25H2 (Build 26200.7171)
Illustrator Version: 30.0 (64-bit)

Steps to reproduce:
When trying to save a new file as a Cloud Document, the “Save” button remains greyed out.
I am correctly signed in to my Adobe account and can open existing Cloud files without issues.
However, Illustrator will not allow saving to the Cloud unless I first manually create a new Project folder.

Expected result:
Saving directly to “Your Files” in the Creative Cloud should work without having to create a project.

Actual result:
No valid Cloud location is detected until a new project is created manually.
After creating a project, the file can be saved normally.

Workaround:
Create a new project folder