Playback problems with Captain Underpance



I have made a rip in MKV format (max quality) of Captain Underpants. When i play the film back every few seconds the picture corrupts with green and pink blocks. All my other films ripped in the same way play perfectly. The max bit rate of the film peaks about 30Mbps bits. I have other films that peak at over 50Mbps without any troubles. I am playing the film from a NAS but have also tried from a USB 3 memory stick with the same problem. If i use VLC to play the film from either source the film plays fine. If i get Plex to transcode at 20Mbps 1080 it plays fine. It doesn't seem to be a bandwidth issue. I have the same prob with 1 other film too. Any ideas please?


Update - I have just tried the same file using Plex for Windows clients and it plays correctly. Are there any tweaks I can make to the Shield version of Plex?