WD Discovery and Windows 10 File Manager

Installed the 6TB MyCliud Home drive and PO’d that WD Access and WD Discovery do not work together.
1st: could not add files to the New 6TB drive from ANY of the maxed out original MyCouds! WD Support recommended uploading to their Cloud, then downloading to the new unit…about a week to do this.
2nd: there’s a USB port on the back of the new 6TB drive BUT you cannot attach the old MyCloud unit to the new one via USB cable!
3rd: ended up copying the contents of the MyCloud to a spare USB External drive (took 3 days), then plugged THAT unit inot the back of the new 6TB drive; created a folder to copy to and waited another 2 days for the copy - success!
4th: THE PROBLEM - WD Discovery reports that 33% of the drive is full BUT when I go to Windows File Mananger, there are NO FILES DISPLAYED. Just a blank folder! Any/all solutions appreciated!

My Cloud doesn’t support to connect with My Cloud Home via USB cable, you can directly drag n drop data files in each other after mapping them in computer. Make sure to use the WD Discovery (Version: 3.0.376) for My Cloud Home.

https://support.wdc.com/knowledgebase/answer.aspx?ID=19588#subject3

Also you may power cycle and reboot device, then try to check for the same storage.