Thanks you all for your answers 
I contacted the support team last Friday and I waiting for them to get back at me, once they processed the previous inquiries.
Regarding your suggestion @pkunk, I already tried to inspect the midplate. I didn’t notice any obvious anomaly. the only odd noticeable thing is a small marker trace, which I doubt is the source of the problem.
Here are picture of the miplate (sorry for the bad lighting):
I’ll just wait for the support advice
Thanks again for your time !