RT-AX88U USB drive not showing manual media server path

[dlt528n]

My RT-AX88U (fw: 3.0.0.4.386_48631) has a Western Digital My Book 4TB USB drive attached. 1 of 3 folders will not list when added to the "manual media server path".

Under Network Places tab I have created 3 folders; Music, Photos and 8mm_Videos. All folders currently in read/write access. Enable share is on. Allow Guest login is off. Maximum concurrent connections set to 4.

Under Media Server tab the "Enable iTunes Server" is off, Enable UPnP media Server is on. Media server name is listed, media server status is idle and media server path settings is "Manual Media Server Path"

I can successfully create Media Server Directory paths for "Photos" and "8mm_Video". However, created a 3rd path for "Music" fails.
The Manual Media Server path max limit is 10.

I have also retried creating the "Music" directory with iTunes server enabled, but it does not help.

<UPDATE: If I select Media Server Path Settings to "All Disks Shared" then the Music, Photos and 8mm_Video folders all are accessible from my Win10 laptop. But I am still interesting in knowing why I can create a manual media server path to the Music folder.>

[jzchen]

Can you try a 4th manual folder after Music? What happens? I tried moving a USB HDD to one of the ports from a computer on my AXE11000. (I store scanned documents on it using Brother software. But although all the folders are accessible through Windows File Explorer I can not select it in the scanner software. I just moved it back to the computer).