If you have multiple committers mapped to you in a repository, you only see commits from one of them by default when adding content to a review.
For example, I made 2 commits recently from a wrong committer string (home email vs work). So I mapped that to my username. Now whenever I go to add content to a review, I only see those two commits. Not the newer ones from my main committer email.
I manually have to switch to the other committer each time.