Failed drive in Drobo 3RD Gen, not really

I have a functioning 3rd Gen Drobo. It works reasonable well (sometimes it will just disappear on my desktop and I need to trun it on and off and then reboot then voila, back again)
The fourth drive went red as a failed drive and the device appropriately redistributed the data and which took a few hours. All the data was secured.
I removed the drive which is a 6TB WD Red SATA drive. The drive is about three years old and I would have it would last longer.
On a lark , connected the drive to an external adapter and inserted the USB cable to my desktop.
It needed initialization which I did and then formatting.
I ran chkdsk /f /r which found no issues.
I then reinserted the drive into the Drobo. Nothing to lose ( I think).
The drive installed as a brand new drive and there are no issues so far.
The dashboard reads it as healthy.

Curious if anybody has a similar experience or comments.
Thank you in advance.

It’s great that you are following your intuition when confronted with a problem, and even testing a frontier here and there!
I wonder If you have ever run a disk utility over your active Drobo? Some of these issues are corrupted directories, and it would be good to know if this was part of your regime as well?

It sometimes takes a little time but that drive will probably go bad sooner than later. I would have a new drive on standby ready to go when it happens.

I ordered a new drive regardless. There are 4 in there right now so I will have one as a replacement nonetheless.

I have never run chkdsk on the Drobo. I will see how that goes.
I have a 3rd gen at home and a 5D3 at work. Retired 1st gen in the cupboard.
Thank you all.

For follow up.
The 6TB drive that “failed” is working fine now that I have taken it out, reformatted, and run chkdsk.
Yesterday, a 4TB drive failed. The second drive in Drobo.
I did the same. Let Drobo redistribute the data to the remaining drives, took out the 4TB drive, ran chksk, reinstalled.
It may be that the Drobo is the issue…
I know am taking a chance, but it does not seem as likely that two different drives go out within a few days of each other. The drives are in the second and fourth bays (top to bottom). Both are WD Red drives.
I have also noticed that the Drobo will spontaneously disappear from my computer. I need to restart the Drobo and reboot the computer to get it recognized again.