So since this update there are new wolves, and their internal name is wolf2

Until the plugin is updated you have to manually make sure players can damage them.
I added a new group:

{
  "name": "wolves",
  "members": "wolf2",
  "exclusions": ""
},​

And added "players can hurt wolves" to the rules.

thanks, fixed in 2.2.4

wolves will be able to take damage from players

entity group is not necessary in 2.2.4 for wolves to damage players if you have the anything can hurt players rule