Hello everyone I believe this is more of a software than HARDWARE issue but if i'm wrong and posted in the wrong spot I apologize.

So I just finished setting up two Solid State drives, below are the specs on both:

Drive 1
WD Blue Solid State 1 TB 2.5 Form Factor
Installed with Windows 7 Ultimate 64
NTFS
In BIOS it appears as "P0WDC WDBNCE0010PNC"

Drive 2
WD Black Solid State PCIE M2 Form Factor
Installed with Windows 10 Home 64 Bit
In BIOS it appears as "WD_Black SN7502TB"

So when I am USING the WD Black (Windows 10) I can clearly see the Windows 7 drive listed in explorer. I can ALSO move files two and from the Windows 10 and Windows 7 drive freely. However when I boot onto the WD Blue (Windows 7) the Windows 10 drive is not listed in explorer. Is there a way to make this drive visible so I can freely move files back and forth as I can vice versa?

Something also to note, this is the following entries in the "Boot Override" section of BIOS
-P2 ASUS (DVD Drive)
Windows Boot Manager (WD_Black SN750 2TB) <----This is the WD Black listed for the first time
P0 WDC WDBNCE0010PNC <----This is the WD Blue Drive
WD_Black SN7502TB <----This is the WD Black Windows 10 Drive listed for the second time?!
ST31000520ASCC32 <----I have no idea what this is, any thoughts?

I had this issue before and made a partition that is shared between 7 and 10 that is FAT32 to have 32GB shared space between the OS's similar to how to share data between Linux and Windows. If that works for you for 32GB of shared space that may be a solution. Other format that might work is exFAT between both but I havent tried exFAT the issue is that Windows 10 is foreign to Windows 7, yet if you add a format that both support you could go that route.Deoends on how you installed the OS's...had they been done seperate with only 1 drive present...which is the correct way to do it both HDD;s would be visible to each other...Quote from: patio on August 20, 2021, 03:28:21 PM

Deoends on how you installed the OS's...had they been done seperate with only 1 drive present...which is the correct way to do it both HDD;s would be visible to each other...

Another cause of windows 10 drives not showing in windows explorer is it is secured with Bitlocker.

Quote from https://kb.iu.edu/d/bavx

When booted into Windows 10

BitLocker: To verify your disk is encrypted using BitLocker, open the BitLocker Drive Encryption control panel (located under "System and Security" when the Control Panel is set to Category view). You should see your computer's hard drive (usually "drive C"), and the window will indicate whether BitLocker is on or off. You'll also see an option to turn BitLocker on or off, depending on its current status.

Another cause of windows 10 drives not showing in windows explorer is it is secured with Bitlocker.

Quote from https://kb.iu.edu/d/bavx

When booted into Windows 10

BitLocker: To verify your disk is encrypted using BitLocker, open the BitLocker Drive Encryption control panel (located under "System and Security" when the Control Panel is set to Category view). You should see your computer's hard drive (usually "drive C"), and the window will indicate whether BitLocker is on or off. You'll also see an option to turn BitLocker on or off, depending on its current status.

I just booted to the Windows 7 drive and noticed this when I tried to enable BitLocker.