I think there is a world of difference between jumping at home, warming up, lessons away from home etc.. and conpetitions. Lessons dont generally involve 12-16 jumping efforts at height straight off the bat. You normally warm up over simple combinations and gradually build up to a course in a lesson. Warm ups tend to be single fences and other horses are in there jumping too. Competition courses tend to be more dressed. There's the commentary and the bell. There are oftem horses in the collecting ring the horse jumping has to leave behind. Its a big ask imo. I don't think it's particularly a height issue but just an overall sense of being intimidated. We have not yet sorted this with Max who goes like a dream in clinics but under performs when competing but our next plan is to compete HC at a local show that allows it and to go in at the same height a few times to see if we can build his confidence in the arena.