OK well it's pretty crappy that I have to post a bunch of rubbish in here before I'm allowed into the useful forums, so I asked on IRC instead since this clearly won't get answered here.
Here's the answer, tl;dr: It's a bug.
[13:24:37] Is it normal that the some of the "receiving addresses" in the Lite UI are shown under "Change" in the Classic UI and not "Receiving"? I've been using addresses assigned as "Change" to receive coins, inadvertently.
[13:25:26] Lion_: it's a bug, fixed in git
[13:25:51] Will the fix move the addresses or just change what is displayed in the Lite UI?
[13:26:02] just the display
[13:26:20] Is there any consequence to having most of my coins stored in a "Change" address?
[13:26:35] no
[13:26:58] there's no difference
[13:27:02] OK thanks. Final question: Can I move an address out of "Change" and into "Receiving"?
[13:27:03] it is just cosmetic
[13:27:10] no you cannot