To any and all ESRI developers that may be reading this I think, well rather I know I have discovered a bug in ArcGIS collector v.10.2.5, build 1006. I'm using a Samsung S2 with Android 4.1.2 and I have created a web map with a couple of ArcGIS online hosted services for editing with collector.
Configuring date fields to display the dates in the format 21/12/1997 18:00 causes the web map to be inaccessible in collector with the message "Unable to open map, try again later". Reverting the display format to "December 21, 1997" solves the issue. Have not tried other formats but just wanted to let you know. If this bug has been posted elsewhere I apologize for the repetition.