BeagleBone black USB_mass_storage connect to Windows partly working

I have an annoying issue regarding getting USB_mass_storage on BBB,
I have created an image :
dd bs=1M if=/dev/zero of=/usb.bin count=64
Formatted it:
mkdosfs /usb.bin -F 32 -I
I have mounted it, copied files to and from it, no problem.
Then I created a USB mass storage :
modprobe g_mass_storage file=./usb.bin stall=0 ro=0
Connected it to a USB port on my PC
It works in Linux but not on Windows. On Windows I can see the drive, the size is correct, but filesystem is not recognized.
With ro=0 I am able to create a partition from within Windows and format it. I can copy files to and from it but when I mount it on BBB I can not see the files copied using Windows. I can still though see the files I copied to the mountpoint on BBB.

Can someone tell me what I am doing wrong ?