Calibre 2.61 running on Ubuntu 16.04 doesn't transfer books to device Aquaris 10 M 10

NB Aquaris M10 standard - NOT the Ubuntu variant.
When I try to transfer to the Aquaris M10's SD card I get this error message:-
calibre 2.57.1
calibre, version 2.61.0
ERROR: Error: Error communicating with device

Failed to create folder named Books in (u'SD card',) with error: 2:PTP Layer error 2002: LIBMTP_Create_Folder: Could not send object info.
2:Error 2002: PTP: General Error

Traceback (most recent call last):
File "site-packages/calibre/gui2/device.py", line 87, in run
File "site-packages/calibre/gui2/device.py", line 584, in _upload_books
File "site-packages/calibre/devices/mtp/driver.py", line 425, in upload_books
File "site-packages/calibre/devices/mtp/driver.py", line 401, in ensure_parent
File "site-packages/calibre/devices/mtp/base.py", line 24, in synchronizer
File "site-packages/calibre/devices/mtp/unix/driver.py", line 352, in create_folder
DeviceError: Failed to create folder named Books in (u'SD card',) with error: 2:PTP Layer error 2002: LIBMTP_Create_Folder: Could not send object info.
2:Error 2002: PTP: General Error

Transfers to Main Memory seem OK but I really want books to go on the SD card.

Can anyone help please?