There is a workaround I found and used to migrate a custom list with attachments from SharePoint 2007 to SharePoint 2013.
Below are steps:
1. Use Access 2010 to import the SharePoint 2007 list into a database
2. From Access 2010 export to the SharePoint 2013 site
When I first exported it, it was read-only (That was issue). So, I had to do it again (import then export) but make sure the database in access was not read only. It worked very well after that. I got all attachments.
Below are steps:
1. Use Access 2010 to import the SharePoint 2007 list into a database
2. From Access 2010 export to the SharePoint 2013 site
When I first exported it, it was read-only (That was issue). So, I had to do it again (import then export) but make sure the database in access was not read only. It worked very well after that. I got all attachments.