Loot chests

Loot chest like the ones that spawn in villages, strongholds, end cities, bastions etc....aren't spawning with loot in them some do spawn with loot but some don't I have a survival work I'm playing on using the Stronghold Below seed and I'm in a bastion and 1 out of the 5 chest I found did not spawn anything and before that it was 3 of the 5 but I left the game for a couple of hours and when I came back the loot had spawned.