If you are on xbox and are struggling to tame a unicorn, there is a bug at the moment preventing you from feeding it whilst riding it (because it's the same button to feed as it is to jump off) I found a work around but it requires a keyboard, I plugged my wireless keyboard in to my xbox and did the first feed with the controller but for every other feed whilst on the unicorn, I just pressed 'E' on my keyboard and it worked 👌🏻