EX 4 raid 5 missing

I have WD my cloud EX4 and 4 hard disk 4T Red raid 5 ,
And one time I face one hard degraded , when i replace this hard and put a new hard disk the EX4 didn’t rebuild .
After that I restart my cloud and when it up didn’t see the raid configuration anyway. !!!

Hello,

Please refer to the following KBA article: https://support-en.wd.com/app/answers/detail/a_id/25488/