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.