We upgraded LEM from 5.5.0 to 5.6.0 this past Friday. When I came in this morning, it said I had a little under 2 days left for DB migration. I had to reboot the appliance this morning for another reason and now it says that we're back down to 0.2405% done and 3 days 13 hours left. Where is this documented in the upgrade manual?
The recalculation is based on the current amount to migrate, so it's not starting over at 1% from your original data, it's at 1% of the remaining 50% (or wherever you were when you rebooted).
Looks like it was overlooked in the release notes, though we did know it was going to happen. I'll check on what happened there.