when you die there is an score showed up in the screen. the score i think is increase if you kill mobs, i test this bug. when you die with a totem of undying the score is reseted to the time that you died. even your mobs kills sence you die is 100+ it will reset. I HOPE YOU UNDERSTAND.
Score shows the amount of xp you collected from your last death.
Can you reproduce the issue in 16w39c?