On my Jenkins I configured:
Source Code Management
Git repository: https://bitbucket.org/username/project.git
credentials: username/
I was struggling with this issue for long, and couldn't find a solution in Jenkins documentation, I found here a solution in Cloudbees support site.
You just need to add these tow webhooks to your bitbucket repo :
https://JENKIN_URL/bitbucket-scmsource-hook/notify
https://JENKIN_URL/bitbucket-hook
And i work for all pipelines even MultiBranch ones.
Hope this helps someone ;)
ADA