Pending changes on the default branch are commits from another branch

We have configured a VCS per project defining "branch specification" and a "default branch" like shown on the image below. 

There is no new commit on the default branch in Bitbucket (our VCS) since the last successful build. Nevertheless pending changes appear on TeamCity when selecting the "default branch". These pending changes are commits from another branch.

Do you know what could be the issue ?

For information, we use TeamCity Professional version 10.0.4 (build 42538).