Okay! Sorry for the confusion then. 
Yes the original post was specifically about another issue, and yours was just a did-you-figure-it-out, so I moved them both together assuming yours was about Kindle readers as well.
As to the single most common reason indents get lost in ebooks: they aren’t actually indents. Earlier you mentioned tab indents. If you mean that literally, where you pressed tab at the beginning of each paragraph, then ebook readers will tend not to see those at all.
If you aren’t sure, use the View ▸ Text Editing ▸ Show Invisibles menu command in the main editor, and check for little rightward pointing arrows in front of each paragraph. Those will be tabs.