I have all throughout DF seen war supply chests be bugged. Today I had an instance in Ohn’aran plains where the dragon lady announced the chest but nothing turned up, and once in Taldrazus where the chest disappeared as we opened the crate. It’s such a bummer to have this happen, because I think these chests add a nice bit of world PvP. But having them frequently bug out is a disappointment.
Sharding in some of the DF zones have been out of hand for weeks now which i think is the actual issue. I believe smaller and smaller player counts force more players cross shards and the only way around it is playing on the active RP servers, which should have sharding disabled by default.