I've setup an AGOL hosted feature service with a NZ basemap (default AGOL supplied option which is a 10.2.2 service and supports offline) and when I go to try take it offline I press download, define the areas and I get the message, "The map failed to download. The map 'title here' failed to download with message: Unable to construct a WebMapLayer". This is with Collector for Android version 10.2.5, build 1006.
Russell, in the hope you see this I've added you to the group ESRI/Eagle Support.