So it looks like my patch to My Tracks to get it to expose the extra information needed for Tracks2Miles got pulled just before the last release because it broke the export to GMail (and dropbox).
It’s a shame it got spotted so close to the release of My Tracks 1.1.5 I didn’t get chance to look at before it went out.
It looks like Android resolves and unpacks all the Parcellable extras upfront even if they are not used by the receiving Activity or Service. So apps not expecting the Track object I was using fail with ClassNotFoundException because it’s not available.
I’ll try and find some time to come up with a new solution as soon as I get some time to think about it properly.