Arch Linux

Description:
There is this very strange issue: if I mount NAS Volume with cifs mount, From pcmanfm, I can access every file on that cifs mounted NAS Volume (play, read, rename, delete, copy-from-computer-to-NAS), but can't copy-FROM-NAS-to-computer any file to my computer from pcmanfm, neither by drag-and-drop or by copy/paste. There is little popup window "Copying Files" with "File operation in progress" "Preparing..." and nothing is happening. If pcmanfm is started from terminal - there is no any error output, popup window just staying there, and nothing happens.
Same thing is also if I run pcmanfm as root.
However, if I use cp command from console (with same cifs mount) then copying works ok.
Also, if I mount NAS Volume in pcmanfm by "smb://192.168.1.5/Volume_1", then copying TO computer works ok
(of course I dismount cifs-mounted volume before mounting by smb - and vice-versa)
I tryed pcmanfm-gtk3, pcmanfm-qt and caja, but problem persist there too.


Additional info:
* package version(s) : This bug started in kernel 4.9.6-1, and is persistant in 4.9.8-1
* config and/or log files etc. : AMD athlon II X2 - 3.4G; nvidia GTX970; 8GB RAM, Fluxbox


Steps to reproduce:
Mount network drive (sudo mount -t cifs //192.168.1.5/Volume_1 /mnt/nas2v1 -o guest,sec=ntlm) , go to mount point, open it in file manager and try to copy/paste some file (some simple text file - size is not important)