You need to a set a key bind for Walk. By default it's unassigned (as there more key binds overall now so I left the least used actions without a default key).
For sitting down and sleep the default keys are X (sitting) and C (sleeping) now. They can be changed of course.
Let me know if you have any other issues or questions with the key binds. For the next patch I want to set up a panel at start up that allows the players to select between different default sets of key binds.
Thanks!