Finished the dlc Dragonborn, and went back to Skyrim. Wanted more dragon souls, so I went to places that had the dragon icon, that were already cleared. Generic dragon was there, and after killing the generic, the dragon did not burn up and gave no soul. You could still loot the inventory though, and the chest was re-filled.

The word wall, of course had no word, but you could still hear the word wall, and see the vibration as though it still did have a word.

Tried this on several dragon spots, and each dragon was the same. No burning and no souls, but each had the chest re-filled. Some of the word walls acted like stated above, but some did not.

Any dragon that I encounter in any other place, did what it was supposed to do. Burned up and gave a soul.

Tried clearing the cache 3x, re-booting, re-loading. Nothing changed.

XBox 360 slim / 250gb / Skyrim, DG, HF and DB installed / all autosaves off / 6 regular saves totalling 60mb / 175gb free / character used was level 48

There is a limit to how many times the game is going to let you get a dragon soul from killing the same dragon, you are not going to be getting any more souls from them no matter what you do. You are going to have to go find some new dragons to kill.

This is a bug that's been in the game since the beginning.

Thanks people for the info. Oh well. As long as I have been playing Skyrim I did not know this. Thanks again. Mods can close this.