Tried to let someone ride along with me today. My “ride along” is checked but no one can ride me/
There’s a talent you may need to select in the skyriding talent tree. (It’s to the right and makes no sense.)
It might not be supported on the mount your using.
I’ll see if I can find the list again, but it was the original dragon riding mounts plus a few others.
Edit: I should have bookmarked it, I can’t find it again and don’t even remember what I was looking up when I ran across it.