Hardware Transcoding broken when burning subtitles ApolloLake-based Synology NASes

Since you’re also using an Intel Celeron J3355 CPU in your DS218+ you should try out the new Synology-Version chrisallen posted a few hours ago:
New Build - Apollo Lake processor
Did work for me with the same CPU.

DL:
Synology - PlexMediaServer-1.18.4.2082 x86_64

Greetings