Are you creating a separate profile and using it to open the chest? If so, that actually seems to be working as intended - every account created on a console that has the pre-order code activated seems to get the guns, key, etc.
If not, then that's probably gonna get patched
But be careful, because the badass rank resetting is part of that bug, and it seems the bug may stem - at least on the PS3 side - from cloning a profile and the game getting confused about how / where to save.