NBT tag CustomNameVisible is not working in mobs, when an entity has this tag it's name is supposed that it's name would be displayed even when the player is not looking at it. This works in 1.7.10 and 14w21b versions, but not in 14w25b or 14w33a as you can see in the first two screenshots.

When you summon a mob (3rd screenshot) this tag is added by default to it as you can see in the 4th screenshot (you can see the NBT tags of a mob by changing a tag, the custom name in my case, by the EntityData command). If you change the tag value to true it doesn't work as you can see in the 5th screenshot.

This tag is useful for mapmakers and I had used it many times in 1.7 versions, please fix this or add a way to always see mobs name.

I know Searge said this two months ago:

The CustomNameVisible tag does not work on animals and mobs, because they have different rules about showing the name. For the other entities it should work.

But this is not true, it worked in previous versions and mobs still holding this tag.

Please don't mark this as duplicated, let the Mojang team check this again.

Thanks and sorry if I have made lots of mistakes writing, English is not my main language, but I think you can understand what I was trying to explain.