On the "New batch job" windows, Add button, the "Open" window has a selector named "Affinity Files" that select several file types besides affinity files (JPEG, PNG, PDF, etc)
Would be nice to have an entry that select only *.afdesign and *.afphoto file types and, please, change the name of former "Affinity Files" to "Image files" or whatever and name this option as "Affinity files".