My new Moto G 4 Plus, August 2016 with Android 6.0.1, would not allow access to photos from a Windows 10 PC and I could not find a satisfactory solution on any forums so here are the steps that worked for me.
Assumption: Your Windows 10 PC has already loaded the USB driver and Windows Explorer recognises the Moto G (4) but no folders are displayed.
Solution:
On the Moto G 4 enable Developer Options and change the default USB behavior from Charge Only to MTP File Transfer.
Disconnect the USB cable.
In Settings/ About Phone/ Tap Build Number (all the way on the bottom) 5 times. Developer options will be shown second from the bottom in settings. Turn on Developer options, under 'Select USB Configuration', select MTP.
exit and plug in the USB cable.
If USB configuration is already set to MTP and the files are not visible on the PC, disconnect the USB cable, on the Moto G 4 Plus go back to Developer Options / Select USB Configuration and change to USB charging and exit, then go back into Select USB Configuration and change to MTP.
At top of screen under Developer option, turn Off (to avoid accidental changes to anything else).
Exit back to settings
Plug in USB cable
Windows PC should now recognise Moto G (4) with Internal storage shown.
Navigate down through this as for any hard drive.
[Also posted on the Motorola/ Lenovo forum]
Assumption: Your Windows 10 PC has already loaded the USB driver and Windows Explorer recognises the Moto G (4) but no folders are displayed.
Solution:
On the Moto G 4 enable Developer Options and change the default USB behavior from Charge Only to MTP File Transfer.
Disconnect the USB cable.
In Settings/ About Phone/ Tap Build Number (all the way on the bottom) 5 times. Developer options will be shown second from the bottom in settings. Turn on Developer options, under 'Select USB Configuration', select MTP.
exit and plug in the USB cable.
If USB configuration is already set to MTP and the files are not visible on the PC, disconnect the USB cable, on the Moto G 4 Plus go back to Developer Options / Select USB Configuration and change to USB charging and exit, then go back into Select USB Configuration and change to MTP.
At top of screen under Developer option, turn Off (to avoid accidental changes to anything else).
Exit back to settings
Plug in USB cable
Windows PC should now recognise Moto G (4) with Internal storage shown.
Navigate down through this as for any hard drive.
[Also posted on the Motorola/ Lenovo forum]