Not sure if others have reported similar in this thread but for those with the ‘inaccessible after short use’ problem on 1.02.04 firmware - I can confirm that Vlado’s first suggestions (not the expert steps) in his post → here ← successfully resolved the issue (at least in my case anyway with a 4TB MBWEII).
Where I was consistently unable to connect to the drive after 6-12hrs I have now been able to connect reliably for 2-3 weeks straight and everything is still running without hitch.
Hope this helps someone keep their hair in place… at least until WD release another monumentally disastrous new firmware.