It seems that currently the Attachment viewer keys on all layers in your map that have attachments.
I have data that uses an approval workflow that passes between a few different groups and then various attributes are marked in turn. I currently use a configurable web app to display the same data symbolized in four different ways for the different stages they're at in their approval workflow. Currently I can only show the 'on deck for approval' layer in this version of the Instant Apps. To be able to keep all of the 'completed' records in the same application would be very nice as we hand the application to cooperators to view the 'on deck' records.