Invisible scene breaks when book goes from Atticus to BookFunnel?

Hi, y’all!

Thanks to my wonderful ARC readers, I was made aware that SOME (not all) of them were puzzled by a lack of scene breaks in my book. These scene breaks show up just fine in the KDP previewer and in my print proofs, but they disappear when they go from Atticus to BookFunnel.

I’ve built 3 books in Atticus previously and not had these issues (that I know of—maybe readers thought I was just fond of abrupt scene changes?). These are not ornamental breaks…just a big hunk of white space with the subsequent paragraph appearing flush-left (left-aligned). Which is just how they appear in KDP and (weirdly) when I download my BookFunnel book to my laptop or on my phone.

Here’s what I tried:

Deleting the scene breaks and replacing with “fresh ones” (which actually fixed ONE of the “invisible ones”)

Replacing several chapters’ worth of scene breaks with “fresh” ones (which apparently did nothing to help)

My book launches on July 1st, and I’m not worried about the scene break issue with KDP (which Atticus help desk told me is a big enough entity that they scrub any issues clean), but (according to Atticus): “…sideloading is inherently nondeterministic. It bypasses the standardized process publishing companies use to load books onto devices, that ensure your ePub will appear consistent across all devices. This is why your book appears correct on Kindle Previewer, as it goes through KDP's standardizing process to ensure all attributes are maintained. The majority of users should not see this issue, but it is an inherent risk of sideloading.”

Has anyone tussled with this before? Any thoughts (other than going thru the whole manuscript and adding true ornamentals so that BookFunnel will recognize a scene break when it bumps into one)?

Thanks!

Marline