summary:
I downloaded 24 episodes of a TV-series and placed 8 files within reach of PMS.
no subs were dowloaded.
about 12 hours later I added another 8 files. again no subs.
next day I added the last 8 files, but still no subs.
after doing Refresh All, etc.etc., no subs were downloaded.
next, I did a full Plex Dance, which resulted in 11 out of 24 subs.
for the missing subs I did individual refresh, without any success.
next morning, the missing subs were in place.
currently downloading another 24 episodes.
we’ll see how that turns out 
