Maybe she has done lots of schooling and jumping in the school and got stale. It could be that the previous riders couldn't handle her out on hacks if she gets a bit busy (which is what it sounds like) Maybe she is one of those horses who really needs variety in her life. Maybe previous riders got scared and didn't take her out much. I think we have all come across that situation at yards.

Perhaps doing the sponsored rides and fun hacks in between the school work is what she needs to keep her interested in life. Some people never ever seem to go outside the school and the poor horses get bored out of their brains. A bit like kids having to go to school every day and never having any play time I suppose - in the end they stop listening to the teacher. good to hear it is going better.