Desktop Client Cannot Sync Storage Mounted to NTFS Folder

I purchased an additional M.2 internal SSD to expand the space available. Since this was to hold my large photo and video library, which is in NextCloud, I set it up like this:
Original setup: “C:\Users\Bryan\Nextcloud\Photos” and “…\Videos”
New setup: “C:\Users\Bryan\Nextcloud\HDD\Photos” and “…\Videos”
The drive was mounted in “C:\Users\Bryan\Nextcloud\HDD” using the “Mount in the following empty NTFS folder” option in Windows, so it is mostly seamless to the user.
The desktop client does not appear to synchronize these directories. I presume that the mount location redirects in the back end and so Nextcloud does not follow it. If you attempt to “Add Folder Sync Connection” to point Nextcloud to the location, you get the error message “Warning: There is already a sync from the server to this local folder. Please pick another local folder!”
It seems like there is an opportunity to add some logic to the client to either sync that location, or allow you to specify that location to force it to sync. At the moment, it simply ignores it. I may be missing a configuration somewhere, so please let me know if it is my fault. I do not want to create duplicate folders from a mount drive (D:\newfiles) that will then sync into my %userprofile%\Nextcloud drive because that needlessly doubles the amount of space I am using. Is there a way to sync these files without duplicating them?
Also, as I was playing around trying to find a way to not duplicate everything it seems that removing a folder sync connection does not return the icon to the default folder, but leaves it with the nextcloud icon.
Kind regards,