The logs show that MCEBuddy can’t access your file: (just look for “ERROR>” to see why something failed in a log)
ERROR> 2017-10-05T06:46:29 MCEBuddy.Engine.ConversionJob → PreMeta Source file has been renamed or deleted by custom command → \Disk8\Plex\TV\NOVA\Season 44\NOVA (1974) - S44E13 - Secrets of the Shining Knight.ts