[ldolse]

Glad heuristics worked for you. I'm not versed in odt sourcecode, I had meant for you to paste in Calibre's html output (which you could get from the debug output now that I see you're outputting to Mobi).

Anway, I don't know ODT formatting well enough to understand how indents are defined, but during conversion from ODT to HTML calibre must be using Non-Breaking-Spaces to represent indents. Why it's using a variable number of them is unclear to me, but that must be what it's doing.

The heuristics option takes any number of non-breaking-spaces >= 2 being used to represent indents and converts them to a css indent. At this time any number of non-breaking spaces gets converted to the same indent level, essentially normalizing it for you.