Thank you both for responding.
I test played a few files and Ottokerner was correct. It starts transcoding as soon as I activate subtitles. I’m guessing there is no way to stop this short of burning them in which I would rather not do.
I also checked the audio bit rates of some of my other files. They must have increeased the maximum bit rate, because I have files with bit rates higher than 256 that aren’t transcoding.
Thankfully, the hit on the processor is light so its not a huge deal.
At least that clears of the mystery of why Plex was transcoding.
I do have an unrelated question.
When I load up files in Handbrake (latest version) sometimes automatically detects a size smaller than the source file.
For example, if the source file is 720 x 480, Handbrake selects 710 x 480. The difference is not consistent.
I used to manually adjust it but I noticed something odd on an encode of one of my movies. Manually adjusting the parameters seemed to move the sub titles up a bit.
I haven’t done a side by side comparison so it could have been my imagination.
Should I be manually adjust the size or is there not harm in leaving it as is?
EDIT: I’m using a Roku Premiere +.