I have finished the first mastery schedule for Beginners Japanese and have enabled displaying kanji and set "kanji -> " in the settings for.the schedule but I never get shown any kanji on its own. I can't see anything in any mastery schedules for Kanji either. I feel like I'm missing some setting somewhere but I feel like I have looked everywhere and haven't cracked it.
In renshuu, words and kanji (and grammar and sentences) each get their own kind of schedule. To study kanji, find a kanji list that you want to study (like JLPT N5 / Starter Kanji) and schedule it. Once you start learning the characters, renshuu will automatically start using them in your vocabulary quizzes.