Same here on two devices, device 1 stays at Downloading 0%, while the other stays at 100%.
Device 1, shows > 20% CPU consumption for the "Delivery Optimization" process, with some network receive activity (<1Mb/sec.). Both process and network activity stops after 10-15 minutes while the download status remains at 0%
Device 2, shows > 20% CPU and some limited network receive activity (<1Mb/sec.), DL status is now at 100% for more than 2h.
This whole process restarts after system reboot.
Update:
Device 2 successfully updated (took 3h25' to finish)
Device 1 is now at 100% download. "Delivery Optimization" process is still at > 15%, memory consumption ~30MB <-> ~70MB, little or no network activity, very low disk activity.
Wonder what Delivery Optimization is actually doing.
Looks like we need to be patient with this update.