Disconnect after getting bonus chest
I strongly recommend you open a ticket so you can work with Customer Service to troubleshoot this. If it’s a bug, it’s not very widespread.
FYI as far as I can tell, no one has ever “lost” the contents of the chest due to DCs or otherwise. The contents should be in your inventory, even though the bouncy chest is no longer visible (the same thing happens if you have a certain number of bouncy chests and swap characters — some of the chests are auto-opened to inventory).
Good luck and please let us know what you find out.
John Smith: “you should kill monsters, because killing monsters is awesome.”