Writer keeps (randomly?) indenting paragraphs after save

This is driving me nuts (LibreOffice Version: 5.0.1.2 (x64) on Windows 10.)

Every time I open a particular document, Writer will indent every paragraph what seems to be a random amount. First it was just my Heading 1 and Heading 2 paragraphs. Then it started doing it to all of them. Sometimes the body (“Text Body”) is indented one amount and the headings are indented a different amount.

To fix it, I select the entire document, set the paragraph indenting to 0 across the board, and close the doc. But when I reopen it, the indents are back. So even if there was something odd in the document, once I saved it, the paragraphs should have been indented properly.

Any ideas about this? Why would it keep assigning indents to my paragraphs? This is a pretty simple document, too – mostly Text Body with a few Headings here and there.

Thanks for any ideas!