Red, then lights out but working

Having a bit of a strange situation with my MyBookLive Duo (RAID 1 2TB)

Noticed the light was red for short time today then it went out completely.

The drive is still accessible. when I open the UI and go to Storage, both drives are reading as ok.

When I run a fast diagnostic, it’s saying that drive B is bad so I tried replacing it with a spare but it won’t take a non-wd branded drive that I had.

I’ve ordered another drive and put the B drive back in and it’s rebuilding now.

So the drive is running, raid is almost rebuilt, all data and the UI are fully accessible, but no light. All light colors were working previously, so not sure what is going on.

Anyone seen anything like this before?

Ran a full diagnostic and it comes up showing everything is ok. Rebooting brings up the blue light, then red, then no light while the drive is active. When it rests, light goes to blue.

My thinking is that the green led is no longer functioning. During boot up, the red light is showing instead of yellow because there’s no green led that works (green and red lights together make yellow).

So I think the drive is ok but it’s just the green led that is no longer functioning.