I have four horses who don't seem to be able to train. All other horses do, but these ones don't go away. I can't seem to figure out why - horses are fed, riders paid, they're not schoolmasters?

I've had this issue before and it fixed itself when they died, but I don't want to wait that long

https://1drv.ms/i/s!AvJvCAcK5E_milj8P8ORcEp7UXGn

Edit: Sorry this is the only way I could attach a photo