Resolution: Cannot Reproduce
Minecraft 16w03a, Minecraft 1.9.1 Pre-Release 3, Minecraft 1.9.2, Minecraft 1.9.3 Pre-Release 1, Minecraft 1.9.4, Minecraft 1.12.2, Minecraft 1.13.1
EDIT: Was unable to find specific cause for the problem, will post crash report
Teleport away from spawn chunks before doing any of the below.
Summon armorstand using below command:
/summon ArmorStand ~ ~ ~
Create testing objective
/scoreboard objectives add testObjective dummy
Set objective to sidebar:
/scoreboard objectives setdisplay sidebar testObjective
Set 'tank' score:
/scoreboard players set @e[name=tank] testObjective 1
Afterwards, unload chunks by teleporting away.
tp @p ~500 ~ ~
Notice that the score on the sidebar dissapears, proving that the score resets after the entity is unloaded.
Steps to reproduce can be found in this comment