i got all 4 on one toon but then went to get another on an another alt to sell got three chest but forth not spawning ?
May have already looted it on that character.
Logged in specifically just to confirm that yes, if no chest is spawning then you have at some stage looted that chest on that character and either deleted the item or banked the item. Easy solution, log an alt that you know will have never looted the chests previously. I used a boosted alt which I know has never been to BOA to etc