Perhaps you have too much advantage in the army and therefore + the basic value of improving relations * the value of the complexity of the battle is closer to zero.
Yesterday I played. Won the battle 300 against 450. +1 to the relationship.
I won 350 against 700, and got 0, and i mentioned in bug description that the issue is present despite of army size, and overall i had a lot of such battles, more then 40 times already, and haven't received any relation score even once.
Desctiption: Whenever Character helps ally lords in their battles, he does not receive positive reletionship with them, despite army size and battle difficulty.
Steps to Reproduce:
1. Be a part of any faction either mercenary or vassal
2. Find any ally lord battle on campaign map
3. Help the...