File Explorer Help?

I can't find any setting or info on the internet as to why one of my drives is not showing on the left hand side of the File Explorer window....
Things to note: the drive in question is a software raid, syncing is done
Anyone have any ideas?

 

(FYI) I know nothing about raid so I might be way off. Can you go into Disk Management(right click on the little window on the lower left) and assign it a drive letter?

What RAID type is configured?

I believe it's RAID 1 (mirror).
I will hold off on the drive letter change as I don't want to risk messing up the Raid, although I'm pretty sure myself that changing the drive letter will not affect it in any way.
FYI - this is a fresh install of Windows 10, the raid was initially configured in Windows 7, then reinstalled 7, then updated to 10, then reinstalled 10 - so I basically didn't mess around with it at any point.

I believe that you address the array with Raid1 rather than the individual drives.

I believe that you address the array with Raid1 rather than the individual drives.

I'm sorry but I don't quite understand your suggestion....
Are you saying that changing the drive letter might actually work?

This may be not directly relevant, but still useful.
Could you fill in your specs your hard drives (with size)?

Please fill in your system specs

Please follow this tutorial and download the tool. The tool will give you detailed information about your system specs, please fill in your system specs more completely.

How to fill in your system specs:

This may be not directly relevant, but still useful.
Could you fill in your specs your hard drives (with size)?

Done.
EDIT: Changing the drive letter did not fix the issue.

I did not suggest to change the drive letter. My thought was that the 2 disks have only 1 address if they are in a Raid1 array.

They do...
I can't think of any reason why it doesn't show up on the left side....it did in the previous Win10 installation.