If you build on the commandline the classes.dex is included, but if you build in XS it doesn't get included.
Jon and I aren't sure exactly why there is an issue with this when building in XS but we managed to get some more data on what was happening. He's continuing to look into it.
moving to android for the time being whilst his investigation is underway.
Did we ever figure out what was going on with this? Was this because of Microsoft.Bcl target files?