Listing workflow runs with a branch filter omits some results

I’m looking to use the List workflow runs API along with the branch filter:

/repos/owner/repo/actions/workflows/worflow_file.yml/runs?branch=some-branch

But I’m seeing that some of the runs are missing from the results. I do see the missing entries if I don’t specify a branch:

/repos/owner/repo/actions/workflows/worflow_file.yml/runs

I can provide more info if needed.