Instead of a simple ctrl-pickblock and cmd-pickblock to get a block with NBT data, you need to do ctrl-pickblock (with no effect other than allowing for: ) cmd-pickblock which gives you the block. You need to use ctrl-pb and then cmd-pb in that order to get a block with NBT data.
MC-77664
OS X ctrl-PickBlock and cmd-PickBlock don't work
Resolved
Cannot Reproduce
0
(Unassigned)
Unconfirmed
Minecraft 1.8, Minecraft 1.8.1, Minecraft 1.8.2-pre4, Minecraft 1.8.2-pre5, Minecraft 1.8.2-pre6, Minecraft 1.8.2-pre7
Retrieved
I cannot confirm this, it may be an issue with using control/command as your pickblock key. I use F and Command+F works fine to get NBT data.