I have a working collector App on through my organization AGOL account. A simple point feature class. Works great in desktop, AGOL, etc, including adding attachments (photos). Works great on numerous mobile devices in collector, as well. Can record a new point, synch, edit delete points, synch, add 10 points, synch.
It all fails when I add a photo attachment. Add a new point with attachment, will not synch. Edit a point and add attachment. Will not synch. Photos are about 2.5 mb. Of course it fails with a very informative error message: Sync Error a Error occurred while synchronizing edits. Operation rolled back.
On the iphone, if I go back an edit the point and delete the attachment, it will then sync.
On the monterra, even if I go back and delete the points that had the attachments, it will not synch. In other words, on collector for android, even if you remove whatever edit is causing a sync to fail, you're screwed. Just lost your days worth of data collection.