No thumbnails

I recently installed Kodi to my Sony 940D 75″ Android TV.
Everything looks ok and I managed to link to my NAS via Ethernet cable connection. However in the video there is no thumbnail shown even I have selected the view > thumbnail from the menu.
Before using Android TV, I have Kodi setup as HTPC and thumbnail working perfectly.

This his how the structure/folder to show the thumbnail that works in PC:
folder/subfolder/movie01.mkv
folder/subfolder/movie01-poster.jpg

Hence for each movie I have my own jpg file as the thumbnail and saved as the movie file name + “-poster”.
But in Android TV none of the thumbnail shown. Any separate setup need to be done for Android TV?
Thanks in advance for any advise provided.