We're using the branch API build throttle, limiting builds to 12/day. A newly triggered build happily sits in the queue. The only way for me to force the build to happen now, rather than in (at most) 2 hours, is to change the job configuration. Clicking on "Build Now" on the job in the build queue changes nothing.

 

Expected:

Clicking "Build Now" on the job waiting in the build queue should trigger the build immediately, regardless of build job throttle settings.