Markups are very handy and the exchange between Android smartphones works very well with a .markup file (via email and WhatsApp). Same way of exchange from Android to iPhone also works fine - but from iPhone to Android it fails.
There's also a problem with sharing markups via ArcGIS Online for a group. The markup is visible in ArcGIS Online, but not visible in maps shared with this group.
@TamT We can reproduce the problem as well, sharing markup from iPhone -> Android. I'll get a bug entered and we'll see about getting a fix into an upcoming release.
