I find it interesting that you try to get premium sign ups. I myself have an interest in doing and will do later, as long as the problem I face now is solved:
I have two chromecasts, which I named the "TV room" and "room".
When I put paired videos with my computer to be displayed in "TV Room", the subtitles appear normally as they always appear.
However, when I put it to be displayed in "room", the subtitles do not appear. And yes, I checked the subtitle files.
Would you like to know why this bug occurs? Why display the caption on a chromecast and not display on the other.
The LOG file is attached.
My Location: São Paulo, Brazil.
I await an answer. Thankful.