Quick note: I am posting this as a new issue because all the other entries seem to be closed because the others didn't submit their bug report properly.

Mode: Multiplayer and Singleplayer

Steps to reproduce:

1. Create a new single player world, or enter a server as operator
2. Be in creative mode
3. use the command:

/give @p spawner{BlockEntityTag:{SpawnData:{id:"minecraft:sheep"}}} 1

      4. Place spawner

Expected result:

The spawner will function with the NBT data and continue to spawn sheep.

Actual result:

The spawner will spawn a couple sheep once, and then revert to a pig spawner (the default spawner) and start spawning pigs.

Additionally, if you are in survival, it will just turn into a pig spawner WITHOUT spawning sheep one time.