New My Cloud Mirror Gen 2 8T - Adding USB Drive web admin freezes

I have a My Cloud Mirror Gen 2 8T and it seems every time I add my USB WD 3T external drive the whole NAS freezes… I cannot access the web admin page … any ideas?

The following articles may be of use

https://support.wdc.com/knowledgebase/answer.aspx?ID=17364
https://support.wdc.com/knowledgebase/answer.aspx?ID=15071