the monthly traffic allowance is just "OVH to Internet". "OVH to OVH" and "Internet to OVH" is free and not counted.
The information in the manager refers to "OVH to Internet", which is the relevant to know if your server is over the monthly quota.
Hope this helps
Does the currently monthly bandwidth usage in manager count free OVH to OVH traffic?
And does it count download or only upload?