I'll fix this in the next version 2.3.11
(this is happening because for some reason RemuxSupp isn't processing your WTV file properly)
Meanwhile for a work around do this, open the installation folder for MCEBuddy, under the folder RemuxSupp, delete all files EXCEPT remuxsupp.exe
It's important to leave that one file behind and delete the rest. (this is cause remuxsupp to fail and fall back to ffmpeg to remux the file). If you delete remuxsupp.exe MCEBuddy will throw an exception and crash.
That should solve your problem.