The EASY NPC mod attackable option doesn't work on 1.19.2. It only works when you shoot with an arrow at the npc but not with a sword or a punch.

This should be fixed with 4.3.0 where the attributes are automatically reloaded on the client and server after a change.
In former versions you need to "re-spawn" the NPC after setting the attribute so that the attribute is known by the client and server side.
See: https://github.com/MarkusBordihn/BOs-Easy-NPC/wiki/Attributes#abilities-

If this is still not working, it could be related to other installed mods for example the Project MMO mod requires that you have the right skills even if you are in creative mode.