I have converted one of the parameters in my project from a statically defined Choice dropdown box to an Extended Choice Parameter in Single select mode. When I execute builds from the web interface everything works fine. When I try to remotely trigger a build using the HTTP GET interface I get an error and my extended choice parameter does not appear in the list of parameters for the build.

I did notice that I'm running one minor release behind, but there was nothing in the diff from 0.26 to 0.27 that made me think it could impact this issue. I will be upgrading as soon as there are not currently executing jobs.