mkvmerge: Timed Text subtitles inside MP4 container is not identified

Hi, Mosu.

I've uploaded to your ftp "Your Friend the Rat (2007).mp4" file where mkvmerge can't identify "Timed Text" subtiltes inside.

File's MediaInfo: https://pastebin.com/qgm9jhSV

MkvMerge output: https://pastebin.com/R4ARXYPz

MP4Box output: https://pastebin.com/9T3YDaiW