I rarely use next links either. Been known to do so in "Jokes" occasionally. Tend to open a thread, then either come back out to the home screen to select another, or hit the 'back' button, or choose from the 'Latest Posts' The next links work on my android tablet so must be browser or computer related somehow.
As for multiple options, I'm uncertain what the described issue is. It's a pain that the whole list doesn't come up any more, but an individual category will expand if the + is touched. You just have to keep guessing which category might hold the forum you're looking for. Will probably pick the right one after ten or twelve goes.