Confusion about reference branch

the SonarQube version is * Enterprise Edition Version 9.9 (build 65466)
I set the new code definition option is Reference branch, Reference branch is develop,
my branch is fueature/XXX, when i commit many times , the latest scan report display the new lines is zero. my question is that ,why the new lines is not the whole diff between my branch feature/XXX and the reference branch develop ?

Hi,

Welcome to the community!

What has changed in your branch? Have you made code changes, or only changes to non-code files such as configuration?

 
Ann