Ah yes I read that post and I just went back and read it again.
For me, I use lump (RO or Cowboy) not K for smoking so I have no experience with that.
Second I bury my wood chunks. I normally fill the ring about half way, throw in my chunks, cover so the ring is full and start it with about 3/4 full chimney starter with lump also.
Sometimes depending on how much I'm cooking, I will throw a chunk or two on top as well prior to putting the lit lump in. I also do not wait to put the meat on. Once that lit lump get thrown on, I put the meat on and adjust from there. I normally start with the vents basically closed (about 10%) open. This is mainly because I live right on the water and it's normally windy. Temp normally comes to rest at about 200 but the top grate temp settles about 225-230 and I'm good to go.
Even with it burning down to the chunks I have not experienced anything like you mention. Considering you are only using one chunk of wood, I don't think the wood is the problem unless there was bark on it or maybe it wasn't dried out enough. I mean by all means char it a little to try something new but I would consider trying to use something other than K or as another experiment, day that you are going to cook, go to the store and buy a brand new bag so you know that it hasn't been sitting in your garage or where ever you keep it and it's been raining and the moisture may have effected it. Maybe grab some other wood chunks also like Hickory.