As for npcs...

if (corpse.IsValid())

Removing this doesn't fix it. It only appears to, but without this check it will just throw the NRE that you found by removing it.

I believe I've found the issue on why it works randomly, and fixed it in the next update. This is the fix:

                if (entity is BasePlayer)
                {
                    var npc = entity as BasePlayer;
                    var npcId = npc.userID;
                    var pos = npc.transform.position;
                    var entId = entity.net.ID;

                    NextTick(() =>
                    {
                        var corpses = Pool.GetList<NPCPlayerCorpse>();
                        Vis.Entities(pos, 3.0f, corpses);
                        var corpse = corpses.FirstOrDefault(x => x.playerSteamID == npcId);
                        if (corpse.IsValid())
                        {
                            damageInfos[entId].OnKilled();
                            lockInfos[corpse.net.ID] = new LockInfo(damageInfos[entId], Instance.config.LockNPCSeconds);
                        }
                        Pool.FreeList(ref corpses);
                    });
                }

As for bradley and heli I am not sure yet. I believe it's because the initiator is lost somehow. I will check this further

It seems that the supply signal lock is not working.

The fast fall of the supply box still slips through the ground.

All are the latest versions.