MyCloud and Twonky, not showing Thumbnails on TV

My Cloud OS 3 Personal & Network Attached Storage My Cloud
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what i did to fix the thumbs is to log into Twonky via your web browser   http://192.168.1.youtIP:9000/#status click advanced then click clear cache then save then click Rescan content folders.   that should work.  I has the same tumbnail for 90% of my movies until I did that.