I'm trying to get a lever that can only be placed on magenta wool through the /give command, and no matter what i do... i get "can be placed on missingno" which i went into adventure mode to test and see if it was a fancy name for magenta wool... and it wasn't. This will be fixed in the next 3 months, and if it's not a glitch, and i can't make levers that can only be placed on wool... then it will be a change in 1.12.
Linked issues
Comments 2
CanPlaceOn and CanDestroy don't use Data Tags
https://www.reddit.com/r/minecraftsuggestions/comments/3h0jx5/allow_candestroy_and_canplaceon_to_use_data_values/
The command he was using was
/give @p minecraft:lever 1 0 {CanPlaceOn:["minecraft:wool 2"]}
What's the exact command you're using ?