Package... keeps failing: "Cannot copy necessary linked file(s)"

[Typorator]

Hello.

I'm being frustrated by this error message when trying to package a document: 

"InDesign could not package the file 'Filename.indd'. Cannot copy necessary linked file(s)"

I've deleted all images, restarted repeatedly, have no preflight errors and recently updated to the latest version of inDesign (15.0.2).  The primary suspects at this point are 2 (two) linked CC Library graphics (with .ai extensions) that have about 150 combined instances in tables across dozens of pages. The Links panel shows the cloud icon for both of these (CC library) graphics saying 'OK', and all other links in the document are to .ai files with short filenames and no spaces, slashes, etc.

Other files Package without a hitch and there isn't even a warning triangle in the Package dialog box. Please help. 

[Typorator · Accepted solution]

Update: A slash I did not create was in the filepath.

Solution: Select every CC library graphic in the Links panel, then from the flyout menu choose Utilities > Copy Link(s) to… and save the graphic(s) in a regular folder.

This got rid of the slash(/) between the CC Library name and the name of the graphic, replacing it with a colon on the Mac (probably a backslash on Windows). Packaging worked after that. Hope this helps.