FAT32 and exFAT are recognized by both Mac and Windows PCs. Then finally apply the settings and let the drive partition.Maybe bootcamp only likes MBR partitions ~ hope this solves your issue. HFS+ is one of the primary file systems of macOS. Macs use HFS+ or APFS format, whereas Windows computers employ NTFS. Select Imaging devices and then try to Update the Neat Scanner driver by Driver Booster.
Then Driver Booster will begin to scan all the device drivers on your computer and offer all the available updates to you. It also seems important to disable Windows Fast Boot: Boot Camp: Thunderbolt devices not recognized after Windows 8 upgrade. Then hit Scan on Driver Booster interface. A fast Bing search showed this on first page: Download Thunderbolt: Intel Thunderbolt driver (Windows 8 driver should also work in Windows 10, although I'm not sure if this driver works on your Mac).
At the bottom click options and select "Master Boot Record". Download, install and run Driver Booster on your PC. as you did before ~ OS X Extended for Time Machine, ExFAT or Free space for Windows. WD Security doesn’t recognize the new 6tb My Book Desktop Storage drive on either computer but the drive is listed in the Windows Disk Management section. I am a bit surprised you are having issues because your iMac and OS X version suggests that the drive is most likely formatted using the GUID/GPT partition scheme which Windows 7 should have no issues with reading.Actually, being curious I just tested it with Lion and Windows 7 (no bootcamp):I partitioned a drive with one OS X Extended partition, one ExFAT using the GUID partition scheme and Windows detected the ExFAT partition right away.Maybe it's a derp from bootcamp? Anyway, the options you were reading up on are most likely the solution to your problem.Since you only used Time Machine so far and Windows couldn't even access the drive I assume you have no problem with formatting the drive again losing all data currently stored on it?Go into Disk Utility, select the external drive and click on the partition tab. I’m running Windows 10 and version1.4.0.92 of WD Security on my desktop and laptop computers.