Actually this recent PR removed the use of
boost::lexical_cast. What version of cinder are you using (if master git branch, what commit)?
Not sure if / how it could be related, but
JsonTree does some initial string parsing to support a syntax like
data[foo.blah], maybe it is tripping up on the space in your value.
Probably also worth noting that we're planning to deprecate
ci::JsonTree in favor of just using jsoncpp directly. There's little if any gain functionality wise in using cinder's wrapper, it has some design issues, and requires boost containers, so we'd like to eventually remove it from the build.