The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.
The bug
The method net.minecraft.util.text.TextComponentScore.toString() is not creating a correct String representation. A space and a comma are missing after the name value and the value field with its value is missing.
Current String (1.10)
ScoreComponent{name='[NAME]'objective='[OBJECTIVE]', siblings=[], style=Style{...}}