Some settings are not visible in frontmatter although present in files

[progmars]

I’m using the default Quark theme. I set up body classes using the Normal mode "Body classes" field and verified that it worked fine for my page.

However, when I switched Admin UI to Expert mode, I was surprised to see body_classes missing from the frontmatter editor. I thought that maybe it was stored somewhere entirely else, but then I opened up the page md file in a text editor and I saw that body_classes is present there.

I refreshed the admin UI multiple times - the same result, no body_classes in frontmatter but present in both file and UI Normal mode "Body classes" form field.

What’s going on? Why does Grav admin UI not display body_classes in the frontmatter when it’s present in the file?

I was under impression that frontmatter should include everything I set in the Normal mode dialogs. Otherwise I'm in a strange situation when I can actually configure more things through UI than frontmatter.