When I try to add a scoreboard using the mine bed statistic, it doesn't exist. There is no statistic for that. The following command won't work:
/scoreboard objectives add breakBed stat.mineBlock.minecraft.bedAnd as well as that, going to the statistics menu will not show the mine bed block stat either. There are no statistics for the bed block, probably since beds are technically two blocks.
Does the stat itself exist? If not, that's the issue