I think I've got it fixed! I made a bunch of changes and it still wasns't working. Then I realized that somewhere along the way - probably when I explicitly cast the post_body field as utf8 - that it wiped out any field that had unicode in it. It left the non-unicode fields fine and emptied the ones with unicode. There were only 164 rows so I copied the data over from post_body_default for those rows. Voila! I can now see those in the database!
I'll do it more step by step on my other forums to see which step was the one that helped.
What *is* that post_body_default field for? Is it really a duplicate copy of post_body? Or did I lose some data by doing that?
