Guardians have stopped spawning in chunks known to have temples/Guardians before. Even newly found temples start with 0 Guardians and have the Elder Guardians still.
Disabled ALL plugins on test server with same seed (1.7 world) same issue. Deleted Spigot.yml and Bukkit.yml same issue. Next step is trying CraftBukkit over Spigot to see if it remains.
Game Difficulty: Normal
Seed # 5546053963910972297
Known Temple coords:
X: 9986 , Y: 64 , Z: -11563
Note this is confirmed on both main and test server with same seed #