After some experiments with them, I have always avoided the attachment data type for desktop databases. There are many posts from people having issues with it. I have also had lots of issues with them in Desktop databases.
It is my understanding that the Attachment datatype was added to help with Microsoft's first attempt at as having Access publish to a Sharepoint server with a Web browser based front end.
Boyd Trimmell aka HiTechCoach (.com)
Microsoft Access MVP Alumni 2010-2015