It is not surprising at all that there are frames missing at reel changes because it is common practice to cut off the first and last frame of each real while "building" a print for projection. It makes it easier for the projectionist to put the correct head and tail back on each reel. So, I would expect (at least at the theater in the US) to find 2 missing frames at each reel change. It is kind of interesting that sometimes these frames are mission when converted to video.
I think that it is interesting that there are versions out there that have the frames and versions that do not. I wonder which is intended? It is possible that an extra frame was left on each reel in order to account for this practice.
This can give some insight into which versions (on video) share comon ancestry (from the same print).
I also wonder if cutting these frames is not practiced at certain facilities, and is at others.
The materials that would be transferred to home video are not treated the same way, so the point is not really relevant. For telecine, each reel would be scanned independently, without cutting the head or tail.
What might be a factor with interlaced transfers is joining the reels together on a master where the first or last image from the reel is partially interlaced with a black frame.
Back to the print screening, however, some forward-thinking locations do NOT cut one frame in, because as the print travels from location to location, you lose more and more of the heads and tails. At each successive location, projectionists will often ignore the splice that already existed and move to the next frame.