stat.mineBlock doesn't work on cakes at all. If you type it in, you get this error:
[00:04:50] Usage: Invalid objective criteria type 'stat.mineBlock.minecraft.cake'
I presume because a cake isn't broken in the traditional sense.
Opps, I put the wrong command in the description. I had meant to type useItem
However, it seems that it's already used to detect when cake is placed down. I suppose that makes this more of a suggestion than a bug. Thanks anyways, I will be taking this to /r/minecraftsuggestions
In addition, logging in and out will cause the pigman to lose track of the target and go passive. This effect is apparent in single player and can be easily abused.
Quick question to those affected, have you ever used MCedit (or other world editors) on your world, because that will cause this effect if they have not been updated to deal with stained glass.
Can confirm.