My friend plays on Windows 10 and I play on Switch. We play in my world that she joins. We went to the end a few days ago after beating the dragon and we each got an Elytra. My Elytra works and so do my rockets. Her Elytra won't activate and the rockets do not work. I crafted the rockets but I don't think that's the issue. 

She also has Java and plays on a server there. She was given an Elytra on that server and has no issues with it. 

I have no screenshot/video because it is not an issue on my end.