Jenkins won't trigger build after merging a pull request in GitHub

Merge should be part of a regular push changed request and might not be handled by Pull Request Builder plugin but rather standard github plugin (as it is not a pull request anymore).

I don't know what type of job you are using (pipeline, DSL, ...), but ...

From your logs, I can tell that you have different branches where you push changes on merge, they are "develop" and "feature" while in branch specifier you have origin/master, so it will ignore changes to any of the other branches.

I had to create two different items. One for pull request builder and another for pull request merger.

Whole example/answer is here: Setup GitHub and Jenkins integration for pull request builder and merger

The difference is explained under bullet point 13 and 14. 14. Configure Jenkins project - Nation-Merge is the one solved my problem.

• Refspec is blank.
• Type origin/develop in "Branch Specifier" field.
• Tick "GitHub hook trigger for GITScm polling" option.