Sometimes subtitiles are disabled

I have noticed that in at least one folder with a TV series which include subtitles, when I start an episode, the  subtitle is always disabled, so each time I have to manually enable it. But on almost all all other shows/movies subtitles are enabled on start. Any idea on why or how to force subtitles to always be enabled?
Running Kodi on Raspberry PI II with AutoSubs 1.0.0