I reverted back to the stable version of 1.1.7, removed the images table from the database and refreshed everything and now it seems to be working.
Prior to removing the tables, I noticed that the last character was not only absent from the captions, but from the copyright as well (possibly all metadata?). This only happened during my attempt to upgrade to the latest nightly build. Perhaps this is something to look into. As for my personal issue, resolved for now.