Foldersubstitution /Thumbnails) only working with SMB not NFS


i want to move Thumbnails to an NFS Share on my NAS. This works only if a access this share via smb Protocol.
The NFS Share is mountly via kodi file manager and i can create a directory via kodi - so i think rights should be ok. NAS is a qnap (aka fujitsu celvin). DOn’t know where to search now… stuck on this for hours now…

Device: Rasp Pi A
Installation media: SDcard
Connection: Wired
Power Supply Type: aukru Power
Power specs: 5V-2A
Peripherals: NONE
Storage Device (incl. Network Sharing Protocol): SDCARD, NFS, SMB
OSMC version: OSMC July 2015 2015.07-1
XBMC version: 19:19:11 17.257921 T:3023524400 NOTICE: Starting Kodi (15.1-RC1 Git:Unknown). Platform: Linux ARM 32-bit
19:19:11 17.258116 T:3023524400 NOTICE: Using Release Kodi x32 build (version for Raspberry Pi)
Codecs: any
Audio/Video Output: HDMI
Config.txt Extras:
LINK to uploaded logs in pastebin (must include COMPLETE Kodi debug log)

Working advancedsettings.xml:

mysql 192.168.2.XX 3306 osmcvideodb XXXX XXXX mysql 192.168.2.XX 3306 osmcmusicdb XXXX XXXX true true special://profile/Thumbnails/ SMB://XXXXXX:XXXXX@192.168.2.XX/KODISHARED/THUMBS/

when i change this line:

thumbnails fail with

LOgs: ask me - i send pastebin link via PN

P.S. what i found out was switch to smb created the folder structure - switch back to nfs (without changing anything on the nas) seems to make thumbnails work – new files are placed there… but i don’t know what if new folders are necessary