Adobe InDesign 20.2 not flattening transparency

[Alphabet Publishing]

I updated Adobe Indesign recently and now it is not flattening transparency at all. I am getting files rejected by the printer and I've had to go through and turn every single image's transparency to 100%, and every PNG

[Rene Andritsch]

Your post indicates that you exported PNGs. Is that correct? Or did you export PDFs? Can you show a screenshot of your problem. How did you try to flatten the transparency? Which elements in your design had transparency applied. Native InDesign elements with transparency effects or placed images? You see there are a lot of things that are connected to transparency. Please elaborate your problem in more detail, so we can help in a better way. Thank you.

[Mike Witherell]

Is it happening to 1 file or many?
what are your Export to PDF (print) settings?

[Robert at ID-Tasker]

@Alphabet Publishing

Can you post an error message / report of the rejection?

[Alphabet Publishing · Accepted solution]

Turns out the customer service at KDP was talking through their nether regions. They told me there was a transparency issue, even though pages with no transparency effects were being flagged. Turned out to be a glitch. Thanks everyone.

[Mike Witherell]

PEBKAC!