Yes same issue as (almost) everyone else who posted recently in this thread.
frustrating - it should not be, because the solution was posted several times in this forum thread
Jul 25, 2018 00:37:41.365 [25660] ERROR - [Transcoder] [stream_segment,ssegment @ 0416e6c0] Failed to open segment list 'http://127.0.0.1:32400/video/:/transcode/session/f066675477036652c69cda27d0b3adcf/2f978e1d-0615-4b0e-803f-6fc1e3885af0/seglist'
Jul 25, 2018 00:37:41.377 [20604] ERROR - [Transcoder] av_interleaved_write_frame(): Unknown error
Jul 25, 2018 00:37:41.418 [25660] ERROR - [Transcoder] Error writing trailer of media-%05d.ts: Invalid argument
Appears to be the windows 10 update KB4338819 bug which Microsoft superseded with a second update 6 days later: KB4345421.
Please check your windows updates and pick up the later one. you should be able to download it and apply it manually - if it does not auto update
This was the first post (by @cbabb) in this forum thread that identified the fix
https://forums.plex.tv/t/solution-conversion-failed-the-transcoder-exited-due-to-an-error/234363/145?u=sa2000
