SanDisk Ultra Fit 256GB Thumb Drive

256GB Sandisk CZ430 Ultra Fit USB3.1 Flash Drive

I have been using a SanDisk 256GB thumb drive on my Mac for years.  I just tried to use it on my Windows 7 laptop, and it did not work.  I plugged it into the USB2.0 port.  The drive did not show up in File Explorer.  I could however see the drive under Disk Management.  In fact, I could see 2 partitions; a 200MB EFI partition and one other partition.  I tried deleting the two partitions.  I was only allowed to delete the larger partition, and I could not delete the EFI system partition.  Then I was stuck.  I could not create partitions or re-format the thumb drive.

Here’s what ended up working for me.  I had to plug the thumb drive into my Mac.  With Disk Utility, I right-clicked on the SanDisk Ultra Fit Media  (not a partition) and selected Erase.  A dialog popped up and I entered a Name, selected exFAT for the Format, and Master Boot Record for the Scheme.  That completed very quickly, and then I was able to see the drive on my Windows 7 PC immediately after plugging in the drive.

I hope this helps others with this issue.