I had the same problem with my WES. However, after a long investigation, I discover how it works.
IRCC doesn't care about the scanned paper. It is even not mandatory for your PR process to include the documents. The only thing that matters is ECA#, which you included at the beginning of your process. However, if you had requested a re-evaluation without requesting WES to sent an electronic copy to IRCC, they will not know that you really have a newer copy and they will deny your process.
In other words, the paper you have received by mail from WES does not have value for IRCC. They only trust in electronic documents. If WES did not send it, they will considerer the old date.
Note: WES does NOT send this electronic copy automatically. You need to request them during your re-evaluation!