I tried to add a new friend to my XBOX account, he got the message and accepted my friendship but when I check my friends list he is nowhere to be found. The XBOX app says that he's already my friend in my friends list but I can't find him. So what can be the matter? I have an XBOX 360 and he has a XBOX ONE.
I've not really played or added any new friends on Xbox Live for a few years now. However from what I remember it works more like social media on the Xbox One. You need to follow your friend and he needs to follow you back from what I remember, its a two way process. As you don't have an Xbox One add your friend from the Xbox One app on Windows 10 or Android, get your friend to do the same and you should then show up as friends on the Xbox 360.