I’m not convinced that there was never a stereo track for KotJ or Burial Ground. Not one in existence now perhaps, but it would be odd for an episode midway through the season to be mono when the rest are stereo.
I guess we may never know…
Here’s a reply about it on blu-ray.com forum
Knight of the Juggernaut I kinda get as it was the first episode so possibly time deadlines and being off location in Chicago maybe it wasn’t ideal to do it.
Can’t really explain Burial Ground, only other than the fact that it’s the third episode of the season to be filmed so maybe the Stereo equipment for filming failed or something or again time and budget.
My take on it I take it as a huge win because the usa release is completely incomplete in comparison and just having the two eps audio being mono and not having the extended preview is to me a ok loss. at least it’s a petty much complete we never had a release this complete.