Problem Description

1) Started having issues with playback of files. I was able to narrow it down so far to "Anger Management", however I'm not 100% certain that the problem is isolated to just this series. I am able to regain succesful playback by deleting the subtitles for an episode.
2) Figured that I had switched around Subtitle Agent's a day before so related it to this cause. Therefore removed the "TV Shows" library and readded it.
3) Problem remains.
4) Figured that not too long ago, I had updated DSM to DSM 6.1.6-15266. The version of the running PMS before and after the DSM update is Plex Media Server v1.10.0.4523-648bc61d4 - synology DiskStation i686 - build: linux-synology-i686 synology. As I had not updated PMS in a while, figured I would start by updating that first. Via the "Manual Install" method - updated to: Plex Media Server v1.12.1.4885-1046ba85f - synology DiskStation i686 - build: linux-synology-i686 synology
5) Problem remains.
6) Found out about https://forums.plex.tv/discussion/306910/hardware-transcoding-not-available-after-dsm-update#latest
7) Reinstalled through the method as described in https://forums.plex.tv/discussion/191000/faqs-read-this-first#Q7
8) Problem remains.

Error Messages

I can reproduce the error for the mentioned episodes below on both Web and tvOS playback.

Web (Safari): Conversion failed. The transcoder crashed or failed to start up.
tvOS: Conversion failed. The transcoder crashed or failed to start up.

Troubleshooting Steps

SRT

The Big Bang Theory S01E01 - English - SRT (Success)
Family Guy S13E01 - English - SRT (Success)
Family Guy S15E20 - English - SRT (Success)
Family Guy S15E20 - Nederlands - SRT (Success)

SRT Forced

Family Guy S15E20 - English - SRT Forced (Success)

None

Anger Management S02E49 - None (Success)
Anger Management S02E51 - None (Success)

SRT External

The Big Bang Theory S10E01 - Nederlands - SRT External (Success)
The Big Bang Theory S10E01 - English - SRT External (Success)
Anger Management S02E50 - English - SRT External (Success)
Anger Management S02E52 - English - SRT External (Success)

Anger Management S02E50 - Nederlands - SRT External (Failure)
Anger Management S02E52 - Nederlands - SRT External (Failure)
Anger Management S02E53 - Nederlands - SRT External (Failure)
Anger Management S02E54 - Nederlands - SRT External (Failure)
Anger Management S02E53 - English - SRT External (Failure)
Anger Management S02E54 - English - SRT External (Failure)