I have the same problem. I can attach a picture to a point and as long as I don't disconnect from my wireless or 3g connection, I can see the attachment. If I close out the esri app, turn off the iPad (standby), come back into the esri app, the attachment will still be available.
Once I disconnect from the network, reconnect and try to view the attached picture, a blank white picture is downloaded into the esri app. The images are available via the layer in a desktop environment, so I know the pictures are being saved, their just not being downloaded back onto the iOS app when wanted.
I was thinking database or virtual directory issues, but haven't found anything yet.