I was trying to edit the NBT data of fireworks with NBTExplorer, and nothing happened. (Yes, I did save! I checked!)

Note: This applies to any NBT change.
What I expected to happen was...:
The firework would have the modified duration.
What actually happened was...:
Instead, nothing changed. The NBT data was set back to what it was.
Steps to Reproduce:
1. Make a firework rocket and quit Minecraft
2. Open an NBT editor and change the duration
3. Save and log back into Minecraft. Notice the duration is not what you changed it to

*You could also do this with any other change, such as adding a name or changing the number of items in a stack.