Hello everybody!
I've just got may Mavic, it is my first DJI copter.
When I'm connecting my mavic to Win10's PC via usb, 2 disk drives appears, but only one of drives are accessible. I can see only videos and photos on this drive, other  folders are empty.
I'm not sure, but before updating firmware to last version, many other files (logs, etc.) were present on USB drive.

Is it normal, or I have issue with drivers or hardwаre?

This appears to be a common problem after uploading to latest FW.  I'm hoping that DJI will acknowledge that this was either deliberate (to stop us looking at Flight Data) or a bug in the new FW.  

I think I would be happy either way, I just wish they would communicate these things better.  That said I do find the Flight Data files useful.

This is normal. Our engineers are aware of this case and working on it, please wait patiently. Sorry for the inconvenience and thanks for the kind understanding.