Saddlebag makes an excellent point.
I just recently went back to my 19yr old gelding and treated him like an unstarted colt. I never really realized how bad he was. To me he was the old faithful, but old faithful had gotten into a routine of doing nothing but ponying colts and going on brief trail rides in the past year that magnified his faults and ended up making him sour. He was especially bad because he throws his head, moves, or bites when mounting. I never cared because I had bigger problems to worry about with my main horse and I got so caught up in making her perfect that I didn't address his problems. He wouldn't stp when I said "whoa" either, and he would jig after the first time I asked him to lope. I would always get him settled so I ignored it.
I took four days this week. I went back and did Clinton Anderson groundwork with him. Yielding the hindquarters and forequarters, lunging for respect stage 1 & 2, flexing in the rope halter, laying on him bareback, and yesterday I saddled him and got on him with zero problems and rode him on a loose rein in the rope halter, walk/trot/canter, and he planted his butt and slid to a stop with just me sitting back and saying whoa. I never touched his face. I had no idea groundwork would fix his two main issues. I feel like I have a changed horse.
I suspect your horse could benefit from this too. Treat him like an unstarted colt. Then treat him like he's never seen the barrel pattern before.
Pssh.I didn't pick up the wrong lead
It's called a counter canter...
...A very advanced maneuver.