Thanks for the bug report. I’ve filed it with our QA team, but it probably won’t be fixed too soon.
This will get resolved automatically in the next month or so. We’re actively updating the way emoticons are handled by our clients so that they continue to work as the number of emoticons increases. Long story short, there are too many Twitch emoticons now for clients to deal with them on their own. The chat server will start parsing emoticons and notify clients regarding what text should be replaced in a message.