I'd first contacted Kindle Customer Support a month ago with the following query: why did "chunks of text" vanished when previewed on Kindle's online previewer? I had uploaded the book multiple times and still, no resolution.
The answer that I received was the file was fine. It was the online previewer's fault said the Kindle Team. Download a different previewer.
That seemed odd. But I accepted the team's word and "published" it. Of course, e-publishing is different from print. You can upload to your heart's content. Still, you'd rather not. You'd rather be promoting your book or writing a new one. Uploading's no fun.
Then, readers wrote me that, yes, text went missing on Kindle Cloud, but not on Kindles. Again, a flurry of emails to Kindle Customer Support who assured me, many times, that they were "not able to replicate the problem."
A friend contacted Kindle Customer Support about the missing text (on the Kindle Cloud reader.) She was told to reinstall the software as well as the book title. This would have been a complicated matter, since she had dozens of downloaded titles on her Kindle Cloud. And neither of us felt that this was the solution.
I didn't drop the issue. This morning, I received an explanation of what was wrong with my HTML file. (A simple fix: code had slipped in that specified font and background color, which is a no-no. It took a few seconds to remedy the problem)
Lessons learned: A problem doesn't disappear because someone else can't replicate it. And don't believe everything that Kindle Customer Support tells you.