Does it count when you are a not-so-great rider that just won't put up with BS from her horse? Dancer never refused an obstacle on the trail (for which I am forever greatful as my riding skills have seriously deteriorated!)
My heart horse, Sugar (long since gone) was great on the trails as long as she was in the mood. The first time she refused to cross a wooden bridge, it became a battle of wills. Sugar would try to turn for home, and I just kept making her complete her little spin so that she wound up facing the bridge all over again. After about a dozen spins (I think we were both getting dizzy) she decided to cross the bridge. There were several other wooden bridges on the road that day, but she gamely walked on across. She hesitated only slightly at crossing the overpass on busy I-40 - but responded well to a firm nudge (maybe she remembered the first bridge?) She barely twitched an ear when the semis driving under us honked their loud airhorns.
She flat refused
to walk through the underpass that goes under I-40. Traffic didn't seem to bother her - I think it was the inky darkness and the echos that worried her. The spinning her back around trick didn't work. After half an hour, I couldn't take another spin. I got down (aka chickened out?) and led her through the underpass. Then turned her around and led her right back through to the same side we started out on. She was not going to get out of carrying me under the highway! I guess she figured out there was indeed light at the end of the tunnel, and no monsters in the tunnel after all, because she didn't balk there again.