Mob spawner - "Total mobs spawned" counter resets in civ land

If you shift + right click on a spawner, it brings up a GUI containing spawner information, and the "total mobs spawned" counter. If the spawner is placed so the mobs fall out of the 9x9x9 area around the spawner, the "total mobs spawned" counter will pretty quickly reset to 0. It should count the total number of mobs spawned since the spawner was placed (and it appears to work this way in neutral land) This is most likely related to the "30% faster mob spawns" civ buff