This was caused when the dev went to initially add the act 3 content to the existing files and it broke a lot of the code. Arc said they had to fully redo chunks of the code, including the UI.
chances are some of these things will be hammered out in a coming update, but for now it seems the dev is taking a much needed and deserved break. The last news thing said how all the work he did with the act 3 content negatively affected his health and how he will take at least a week off.