Jetpack has never worked for me on my mobile app (for iPhone). Even with the recent update promising a fix, my attempt to install resulted in the same phenomenon: jetpack was not installed because it already is installed--despite not seeing it listed as one of the installed plugins...I wish I could navigate to some sort of root plugin directory and rip whatever phantom folders are there. Alas, I'm not that savvy.
Come on, Jetpack, throw us a bone.