I had something similiar happening.
Yesterday fought against 3 animals. Peaced out(went passive?) on them at combat start. 2/3 (pig and sheep) were punched to death.
I'm using one pen for all of my animals currently and it got a bit crowded. Just theory crafting here. The animals were kinda stuck near/at other animals and couldnt really pass/move to me freely. Maybe thats what caused them not to yield?
Today I fought against 3 sheeps and taming proccess was succesful. The only difference is that I let them move freely out of the animal pen so they had lots of space to fight against me.
I had 2 other bugs happening while taming:
1. was fighting boar, sheep got untethered and started walking away from my pen.
2. I always tether animals after the fight. Yet my 2 sheeps(from 12 animals total) dissapeared when the area got unloaded. Maybe sometimes hitching post doesn't remember that some other animal was tethered to it and lets you tether second animal to same post?
as a side note: my taming pen is far away from walls so someone agroing them is out of the question
