Importing into new project in Jira Cloud: Getting message that "attachment already exists. Skippin

[Linda Schmandt]

I'm migrating a next-gen project to a classic project and have been pleasantly surprised at how well it works except for one thing:    None of the attachments were imported.   For each attachment, the log file says, " INFO - Attachment 'overlap issue.png' of issue <issue-key> already exists. Skipping"

Since we're in Jira Cloud, the URL of each attachment looks like this:  https://carnegielearning.atlassian.net/secure/attachment/123456/overlap+issue.png

where '123456' is a 6-digit identifier, I assume.     Well, of course it already exists, because I'm moving from one project in my environment to another.   But I want the attachment to be linked to the new issue, not the old.  

What's the right way to do this, please?  thanks!