Filters won't work except on exact match

[Resqs48l]

Special characters attached to a string seem to work fine, but numbers to not. One of my settings is to alert me if a post title containing "X" is posted to a certain subreddit, and multiple times since starting to use this extension I've checked the sub myself and noticed something like "25X" or what-have-you in a thread title that I didn't get a notification about. "(X)" or "[X]" work just fine, and I haven't noticed anything like "X25", though posts are also seldom formatted like that so maybe it wouldn't work either.