It is the same type of error as what others got after installing Windows Update KB4338819
Jul 22, 2018 12:32:25.700 [4844] ERROR - [Transcoder] [stream_segment,ssegment @ 026a4a80] Failed to open segment list 'http://127.0.0.1:32400/video/:/transcode/session/417ef5d3-7a2b-4561-b694-7e999a065921/7d56d0ae-5f7f-4ba7-8a6a-452d8b7bbeaf/seglist'
Jul 22, 2018 12:32:25.704 [4120] ERROR - [Transcoder] av_interleaved_write_frame(): Unknown error
Jul 22, 2018 12:32:25.705 [3284] ERROR - [Transcoder] Error writing trailer of media-%05d.ts: Invalid argument
If you have that update - the fix was in the Windows Update patch set that went out after that as KB4345421
Go through the Windows Update History and list of KBs to see what has been installed with respect to the above two KB’s
If it is not the windows update, it could be security software that is blocking out some 127.0.0.1 requests made by the transcoder
You can also check the OS Build
Build 17134.165 is bad
Build 17134.167 is good
The build number can be seen through
Start / Settings / System / About
