Solved! Go to Solution.
SOLUTION FOUND !
This has been a HUGE problem for me, ranging from the mobile app crashes occurring with .csv files loaded in the map, to shapefiles, and even occasionally ArcServer layers. This ALWAYS happens if you change anything such as formatting/symbols/etc. and will sometimes happen even if you don't change anything.
SOLUTION : Author a map in the arcgis.com viewer, add any files and change any symbols/formatting/thing you want, save the map, re-open the map in arcgis explorer online, save the map in explorer online by hitting the save button. Now re-open the map in arcgis.com viewer and hit save. DONE.
The map will work in any of the mobile apps now, android or iOS. This goes for both the ArcGIS mobile app and the BAO mobile app.
It has something to do with the way in which explorer online "converts" the data to a readable format, but you cannot just open it after you save it in explorer online, you must re-save it in the arcgis.com viewer so the apps see your map as "readable". Clearly a bug in the way the arcgis.com map viewer saves things, but explorer online fixes it!