When right clicking a saddled pig with a name tag it does not name the pig. You'll either start riding the pig, or move slightly when shift right-clicking.
This relates to MC-14525 , that fixed this issue for adult villagers etc., but not for saddled pigs. Also relates to MC-2188 and MC-19033 .
name tag item doesn't work on entities with right click ability
Pig with a saddle loses name and you get the name tag back when chunk the pig is in gets unloaded
Item gets used when right clicking on a saddled pig
Unable to name certain mobs with off-hand