When a job uses the template-project plugin option "Use SCM from another project" and "Poll SCM" in Build Triggers section the build is only started once.
Step to reproduce:
- create a job A
- create a second job B
- in Source Code Management section select Use SCM from another project and select the job A
- in Build Triggers section select Poll SCM and enter a schedule
Job B starts and use the Job A SCM configuration. After this build, whatever the modifications pushed in the SCM, job B build is never triggered anymore.