In the past 3 months, Harley has improved somewhat being ridden in a ring. I finally found a saddle/maker fitter who reflocked my saddle to fit Harley perfectly, and he is much happier. I suspect that some of the saddle issues were connected to the abuse he endured from the dressage trainer who had him a few months before I bought him. I think Harley equates saddle discomfort with the abuse, so his saddle needs to fit exactly. Now it does.
So, after 3 months of watching him closely, I don't know if Harley will ever be happy working in a ring. Out on the roads and trails, he's completely happy. When I ride him in a ring, I can tell he'd rather be anywhere else. He's been that way for most of the 3 years I've had him. I haven't cantered him in almost 2 years. I want to canter my horse. I could do that on a trail, but there aren't any near where I board him. Big problem.
I'll give it a couple more months and see if he is any happier doing ring work. Maybe if I can start jumping him a little, he'll relax. Perhaps he just hates flat work. It is rather boring, after all ;)