Forum posts in the Android app

I've been lurking on the forums lately using the site and the Android app, and a few days ago I decided to make an account. Today I went to log in through the app so I could reply to a comment, but I can't seem to find the option. There's a plus button in the toolbar which I assume is for commenting on a post, but it won't let me choose a comment to reply to. And it doesn't seem that I can write posts or recommend anything, either.

Are these features missing, or have I just overlooked something? I'm sure I've seen comment replies from the app before.