Pre-Metheus Puzzle World in a Bugged State After Completion

Hello,

Just recently, I started up a new world as Wanda. I survived 100+ days on it and did a lot, exploring the entire mainland. After having this world for this long, I decided I would do the Cyclum and Metheus puzzles with a friend, which we successfully completed. I created a new world for the express purpose of completing the final step of the puzzle (in the process discovering that picking any post-Metheus DLC characters would result in being forced to play as Wilson), and we finished the final step of the puzzle and received our skins. 

However, recently, upon attempting to enter my pre-Metheus completion world, I was treated as a brand new player to this server; picked Wanda, was forced to play Wilson, had my inventory wiped and worst of all, my map progress entirely reset. 

I was able to fix this once by rolling the world back, but it's happened again, and each time I roll the world back, I am forced to pick a new character and am treated as a new player, however now, for some reason, the map progress seems to only have what I've travelled since being afflicted by this bug. The bug still happens. My world seems to be in a bugged state where I am occasionally forced to pick a new character when logging in, and rolling it back does not always fix it. 

Please, help.