My lvl 90 rogue as of yesterday was unable to unlock ghost iron lock boxes as I normally do. Not standing within use range of a mail box (in case that matters).
However, based on a tip from another thread, I tried opening the lock boxes through the “will not be traded” portion of the trade window and it worked just fine.
So there is a work around, but normal unlocking functioning is broken right now.
My character is located on Atiesh. Someone on Lei Shen told me they open lock boxes just fine, however I did not ask if they used the trade window to do so.
Updated: the person on Lei Shen said they also used the “will not be traded” window.