Commit tracking lost with Bitbucket integration

Since the last two or three days i've been noticing that when a merge is done from a specific branch to master branch and closing the source branch, the issue's dev section appears empty with a link "Create branch" as it was never created and no commit was ever done...
This is causing troubles in code review and tracking; because it's not possible anymore to see what a developer did to a specific issue, but looking in the master branch's history (which obviously is quite large since everytime a issue is done, a merge to master is done) and is taking too much time.