I recently set up github pull request builder on jenkins and it works well when I commented the trigger phrase on the PR. But when I tried to run multiple jobs by setting the downstream upstream relationship, I met this problem which is jenkins triggered the job job A set up by pull request builder as normal, but wouldn't trigger the downstream job job B when job A has finished.
Here are some of settings:
In job A: just everything on the instruction page of the github pull request builder
In job B: Under Build Triggers section, I checked Build after other projects are built and set the projects to watch to be job A, and checked Trigger only if build is stable (Nothing about github pull request builder on job B)
Try doing this from the upstream project, instead. From the upstream project configuration, Add post-build action --> Build other projects, then enter the name of the project to build.