We were playing in RoyalWithCheese's new Server with this in it and Cheese tames a 168 male horse, it wasn't taming right at first, it wasn't keeping the tame amount. it did perfect tame though. We tamed 2 other females and 1 other male one female was perfect tamed and the male I think was 80%, the one I tamed was like at 60% something percent. Cheese's horse could not breed, the other 3 could.

So I did some testing in my SP and my first 4 can not breed, The 5th and 6th can, one is perfect tame and the 2nd is 80% tame effeciency. They breed fine. I even tried the force fix on the other 4 and they still can not breed. I will try cry podding them later to see if it fixes them.