I have been having the exact same problem
The H command works (fn+F3+H), it allows me to see all of the useful information about an item and stuff
All you have to do for that one, that I have seen, is hold down fn and H at the same time, and then while they are down, push the F3 button, and it works like magic.
Yet for some unknown reason, the fn+F3+B command won't work, not even with the same methods I know the B Button isn't Broken for oBvious reasons...
Perhaps this page will assist in your search:
http://minecraft.gamepedia.com/Debug_sc ... Debug-KeysAny ideas, please help me
NOTE: I run 1.11.2