Converting a position string to MGRS seems to have an issue in 1.1.1. When I call the following code, I end up with the correct zone but the easting and northing are all 0's.
var string = info.position.toGeoString(Position.GEO_MGRS);
This looked familiar to me, and I know why--it was reported early this year, and we got a fix for it put together but it has not yet been brought into a recent build. I've asked for us to include it in the next release, so the fix should be available to you soon.