it's a bug that isn't fixed yet.
to get this to work: (using the configuration on the left photo)
you need to update the block underneath the chest after opening the chest
you could for example put a comparator facing this block
something interesting also:
when you use an "incompatible texture pack" (old texture pack system), the texture for the chest/trapped-chest will still be loaded (in the hotbar, and holding the item in your hand)
David Marshall
MC-6147
it's a bug that isn't fixed yet.
to get this to work: (using the configuration on the left photo)
you need to update the block underneath the chest after opening the chest
you could for example put a comparator facing this block
just found out myself
, thought i'd let you know 
something interesting also:
when you use an "incompatible texture pack" (old texture pack system), the texture for the chest/trapped-chest will still be loaded (in the hotbar, and holding the item in your hand)
already posted, use search option before posting
-> https://mojang.atlassian.net/browse/MC-6147