I moved all your posts from the unrelated topic Windows 7 Server exits after some time - Plex Media Server - Plex Forum to here as the fix that I mentioned in that topic has no relevance to what you were cross linking to
I have also replied to your private message requesting a sample file with logs of the issue on 1.2.6.1 and it working on 1.24.5
Also you mention in the topic here that it crashes - there is no evidence in the logs you provided of any crash for the transcoder or the server
