Hm. For some reason the prior entry republishes to aggregate archive pages but not to individual entry archive pages.
I wonder if it’s the image embed. Man, that would be a pain.
I’ll try rebuilding it here block by block.
Initially, I pasted the image into this entry, and both the aggregate and individual page entries published. Then I pasted the first paragraph above both the image and the behavior of no individual archive rebuild appeared.
So it may be a bad character in the first graf or it may be a limit on the number of times an edit can be generated.
This would appear to be a clue to the export-resistant entries as well.
I’ll continue trying various tricks.
UPDATE: The entry rebuilt, finally, apparently after a full site rebuild. Still, an edit to an individual entry shouldn’t delete the initial post without writing the update. It seems likeliest that it has something to do with the size of the blog’s entry set, which is approaching 7000.