I think you would need to open a Zebra support ticket for that issue since it sounds like an issue with the Mass Storage driver. One potential alternative would be to use USB OTG mode which would allow the cradle to support a USB mass storage device such as a USB memory stick. This would allow files to be copied to and from the MC under the control of the MC application. To test this you just need to have a USB OTG adaptor such as the one shown here :https://www.amazon.co.uk/TECHGEAR%C2%AE-Mini-Adapter-Cable-Female/dp/B00DM6EMQ2/ref=sr_1_8?ie=UTF8&qid=1478781656&sr=8-8&keywords=usb+otg+mini+to+a
If the memory stick is connected via this cable, the USB drive will appear in the file system when the MC is inserted in the cradle and will disappear when it is removed. This functionality is reliable in my experience although I have not used it extensively on a MC3200.