Having same problem - anti theft not compatible with devices. Nexus 6 w/Android 5.1.1, build LMY48W. Also Nexus 6p w/Android 6.0, build MDB08L. Both devices are running Mobile Security 5.0.2-8394-2e09f19. Seems to be the latest update I have received (a beta version?). Hope that Anti Theft will come back soon!