KDP error on a single page (text outside margins)

Yeah, I am aware of all the variables. I've been doing KDP/Lulu/etc. publication for quite some time and usually the rejection reasons are... understandable if not particularly sensible.

KDP in particular uses an almost wholly automated system to process books. It is absolutely opaque and while they make much of "being helpful," simply telling you that the error is on pages 26 and 125 is not usually of any help. You just have to keep changing things until you've properly appeased the ghods, or just give up and do a more vanilla layout. There is no way to reach a human being or advanced AI system that can discuss the issue and/or grant exceptions to the processing rules, even when the rules are wrong. It's... maddening.

An example I've posted before: The book in my sig is published in both paperback and Kindle. (It's a signature example of my dual-format publication methods, besides being a repository of those methods; paging Dr. Recursion here.) In the first edition, I had a back cover blurb that contained the phrase "Also available in a Kindle edition, of course."

It was rejected for "Cover identifies publication as an incorrect format."

I spent three weeks trying to get that copy past the AI review — including putting a "post it note" on the cover art — and finally just gave up..

My current project is a slim little book with an odd internal layout, intended to be a reading companion to a famous American novel. The verso pages are blank — well, they contain space for "Your Notes" — while all the relevant notes for the novel are on recto pages. You can tuck the left side of the book into the novel hardcover and manage it easily. (Frankly, I thought one or another aspect of this layout, such as recto-only page numbering, would trip the AI rejection. But no, I am being allowed to be creative, for a change.)

For further convenience, I want/ed to put chapter number thumb tabs on the pages. There are only 20, and in the original layout they were numbers in text frames with a dark gray background, something like this:

This was rejected several times for "content near the trim line"... but only on a few double-digit pages. No amount of horizontal positioning relative to text safe area and trim margin would pass.

So I laboriously converted all the tabs to images, so that the numbers would not be interpreted as "content."

No dice.

So the current submission has these instead, barely useful enough to bother with but submitted as something of an experiment to see if the AI is just being arbitrary about wholly graphic bleeds:

I await the AI's blessing. 😛

(And for those who do know something of KDP et al. processes, yes, I have bleeds selected and am conforming to all the rules that have allowed things more like the OP's colored page tabs in prior works. As nearly as I can tell from the rounds of cryptic error messages, KDP simply doesn't want any text, or text-like content, outside the inner text margin, not even for "decorative" purposes. The AI simply isn't smart enough — or not given enough leeway — to allow "micro content" like numbered tabs in this region.)