Getting incorrect return from get_commit_diffs()

I'm trying to get the diff between two commit, therefore using this API as,

            ref_heads = git_client.get_refs(repository_id=REPOSITORY_ID, project=PROJECT_NAME, filter=target_branch)
            master_commit_id = ref_heads.value[0].object_id
            source_commit_id = pull_request.last_merge_source_commit.commit_id

            base_version_descriptor = GitBaseVersionDescriptor(version_type='commit', version=master_commit_id)
            target_version_descriptor = GitTargetVersionDescriptor(version_type='commit', version=source_commit_id)

            commit_diffs = git_client.get_commit_diffs(repository_id=REPOSITORY_ID, project=PROJECT_NAME,
                                                       diff_common_commit=True,
                                                        base_version_descriptor=base_version_descriptor,
                                                        target_version_descriptor=target_version_descriptor)

while print the commit_diffs, having output as,

Diffs Response: {'additional_properties': {}, 'ahead_count': 0, 'all_changes_included': True, 'base_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415', 'behind_count': 0, 'change_counts': {}, 'changes': [], 'common_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415', 'target_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415'}

whereas, using curl to set direct REST request, returns correct output.

"https://dev.azure.com/ORGANIZATION/project/_apis/git/repositories/a21206d3-9bdb-41c4-8b77-56f82360a311e/diffs/commits?baseVersionType=commit&baseVersion=b106b44eebeef93d5240f08dca8ceb0124ca4415&targetVersionType=commit&targetVersion=165c197e54d689e9910eb111b9c14e2516184dd8&api-version=6.0"

What is the correct way to use the get_commit_diff()? Or what I'm doing wrong?

Start at the get_commit_diffs() entry point and compare the Python arguments with the REST request shown in the issue, especially the base and target commit descriptors. Reproduce the call and verify whether the returned base_commit, target_commit, and changes match the direct REST response; done means the Python API returns the expected diff.