Did a bunch of testing today, trying to isolate the problem, and it's definitely with the toggles. All other similar features operate perfectly (i.e. accordions, etc.).
I don't think it's a matter of 'levels of content', so far as I can tell, since the accordions, for example, operate in the same way as the toggles but come out in the print view just fine.
I also found that changing the toggles from 'fancy' to 'minimum' didn't always work, so the problem seems to be with toggles in general.
Hope this helps. I really love the service! Hope we can work this little thing out - if we can, then printfriendly will serve all our printing needs and alternative device reading needs :)