Under Android 11 now, the relevant sub-directory seems to have disappeared. The most recent directory choice was to go to phone/android/data/ (assuming you store books in internal memory rather than a card). Drop a book. Read on the Kindle app.
So, last night I'm trying to drop a free book an author gave as a promotion from his own website into that directory. At least before the update, that was easy to do. Suddenly, I can't find the directory. The data under "Android" is limited to four sub-directories which themselves do not contain much. All the books I KNOW are there (since Kindle app still displays them) don't appear. There is no directory called com.amazon.kindle, let alone files under that directory.
For the record, I tried Samsung's My Files, Solid Explorer (with "see Root" and "see hidden files" enabled) as well as Astro. None worked.
Just as the final investigative step, I connected to my computer through cable. There you go. It's all still there. Using the Win 10 File Explorer, I can see everything and move the file in question to that sub-directory.
SO, this is a matter of Android 11 deliberately hiding these directories. Why? I dunno. It's not exactly mission critical stuff here. Moreover, I can't figure out how to un-hide it. It's nice that I can do it connected to my computer, but there are times I'd like to see the files on my phone. Sometimes I travel. I won't have easy access to a computer.
Any thoughts on how to regain the ability to view and manipulate these folders again?