I think it only exports existing curves in the plane. Not sure if that's limited to sketch entities or not.

@Tom I suppose that does work, but if this is indeed intended behavior than it's an enormously disappointing one. Even the help message says "Please select: nothing, with an active workplane (workplane is section plane)" - that does not make sense at all if it's supposed to mean "...after you drew a large thing in that workplane first, then extruded it as a difference in a second group...". That is the exact sort of thing "Save section" should just be doing in the background invisibly for you, not to mention that dealing with a complex object already moving at seconds-per-frame speed adding two new workplanes is extremely cumbersome and extremely likely to crash Solvespace in the process. I may just have to agree to disagree with the devs if this is intended, because it's a bug in my book - but it would still be nice to see some official word on this...

Yeah, I have a similar experience; it's just that I don't always have a convenient flat face to section by. For instance, I'm trying to fit a "as large as possible" vertically set PCB inside a slightly complex plastic box, and a dxf-formatted section would practically deliver me the PCB outline - but obviously there are no faces sectioning the box vertically at its middle point. And yes, I totally can just work back from the internal dimensions of the box and yes I can do the "cut half of it off temporarily" thing to get what I need - it just feels like a monumentally cludgy way to get something that every 3D CAD software should be able to do in its sleep, with its hands tied behind its back - many even let you drag the section plane back and forth in real time; and since the command was right there in the menu, I figured it actually does what it says. Sadly, that doesn't seem to be the case.