Need advice,2 of my WD My Book 4tb ext drive plugged at my Windows 10 PC at the same time,only 1 works

Hi there,
I need help
I had 2 My Book 4tb drive plug at 2 USB 3.0 ports, but my Windows 10 64bit 3rd gen Intel i5 Laptops only recognise one.
the other appeared as : “No writable partition found” at WD Smartware windows , while the other one works fine.
Always the first one works , when plug the second one it never works , always the same when change the drives the other way arround.
But when plug one of My Book 4tb and plug one of my old drive WD Element 1tb both works fine.

I even plug 3 drives at one computer :
1.WD My Book 4tb
2.WD Element 1tb
3.Hitachi Life Studio 2tb
all works fine without a problem,

But when plug :
1.My Book 4tb old tipe
2.My Book 4tb new tipe just bought it this evening
3.Hitachi Life Studio 2tb
The result is only one My Book works while Hitachi works fine.

So I have no idea what’s wrong,is anybody here can give me some help and advice,because when I report this to WD they even suggest me to ask WD community,what a shame.

Welcome to the WD Community.

Sounds like one of the unit is going offline when you connect the other one.

See how the units are showing under disk management, if one one shows as offline, make a right click on it and it should give you the option to change that to online.

How to access Disk Management in Windows to manage hard drives