DL4100 won't rebuild raid 5

I have a DL4100 comprised for 4 Western Digital Red 3tb. So far replaced 2 of the drives with 4tb red. I put in a 3rd 4tb red drive. Drive says is good but the unit will not rebuild the raid. I clicked on manual rebuild and it pass the self test. But it won’t rebuild. I restarted the unit as well with no luck. Any assistance would be appreciated.
Thank you

You can refer the below mentioned link to test the hard drives health status, make sure you run the full test on the hard drives.


You can also attempt the steps given in the link mentioned below to try the manual RAID rebuilding.