Save BUG on PC
I encountered this issue on PC. Game loaded at an older save date/time. I lost a a bunch acts, equipment, and went from level 12 to level 9. You can see from my save files that I am at Jamboree Act 2 and finished all of the Goblin Shard but in the world map it shows I have only completed Act 1 of Goblin Shard.
Nimbus#88540 shared this idea