I was trying to make it so when I make a new post, the MultiMarkdown format was the default. I thought, "how hard could it be?"
I just made some tweaks to the HTML rendering for the page and post type dropdowns directly.
Well, fast forward a couple days.
I had manually tested using the "edit post" functionality but not the "new page" functionality, or even the "new post" functionality.
So what did I miss?
Step 1! And, of course, step 2.
I corrected my mistake this morning by following the steps correctly and all was well.
Whew!
Thank goodness nobody really depends on this software but me. It was only slightly embarrassing. Ha!