I would have expected those particular paragraph style settings to behave a little differently.

The dont add space setting basically changes the space before and space after paragraph settings to zero when paragraphs of the same style are together (but allows the regular space before and after to apply when preceded or followed by a different style. This setting was not relevant to your issue

The mirror indents setting changes the left/right alignment of the even-numbered pages. This is a setting that allows for a binding gutter - Imagine you printed a heap of pages and put them in a book/folder - The inside edge of the paper would need more space because that is where the paper is jammed together (the gutter) and you can't see a centimetre or so of the physical edge on the inside like you can on the outside edge of the paper. This setting offsets every second page to allow for this. Normally this is done with page setup settings but in your case, you discovered it can also be done on paragraph styles. This was relevant to your issue but I didn't mention it because in your screen shot, the left side aligns but the right didn't. I though the mirrored indents setting would have offset both the left and right margins as a pair. I'm not sure why it didn't in your case but that is academic now that you have solved the issue.

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Andrew Lockton
Chrysalis Design, Melbourne Australia