Tanning of wolf pelt seems to be impossible at the moment.
When putting water, gardening lime and wolf pelt in barrel and selecting tan pelts option after lid is closed you get text message about "you need to put pelt into barrel" or something like that. Can't recall the exact message.
While keeping previously mentioned things inside the barrel and adding cow pelt tanning is successful but only for cow pelt. Wolf pelt remains untouched.