I too have this same problem with iphone sync on my windows 10 laptop, a Dell tablet running windows 8.1, and two Desktop PCs running Windows 7. All of my systems are running 6.4.0. On my systems I can replicate the problem by shutting them down, powering them back up, and then try to sync. Like Timo K reported above my name and information about the last sync are missing. It's as if Enpass doesn't know what to sync. I need to disconnect from iCloud and reconnect to get sync working again. KP