1. have a BitBucket repository
2. create a simple Bamboo build plan, with tasks
Then, make trivial code commits to the repository, it did not trigger the build.
There're few possible reasons
1. Please check manual build execution works as expected and Bamboo can checkout code. If there's any issues, save repository settings to refresh SSH key pair for Bamboo <-> Bitbucket Server authorization
2. Check AppLinks status for connected Bitbucket Server
3. Check configured triggers, there should be Bitbucket Server trigger (recommended) or Repository polling trigger