Just started a new game with 1.20 and picked up a unit from a quest with Strength and Muscle, they didn't seem to get any more weight capacity from Strength so I checked it out, and the description just said "AdjustUnitStat" IIRC. Tried to design a new unit with the strength trait, they didn't get any more weight capacity from the trait so... I guess it's broken?
Didn't check any champions (I only had 1 and my sovereign, neither with Strength) but maybe it's the same there?

I am not using any mods that alter abilities/traits (that I know of at least, I am using Huge Maps, Snaking mod, Cuztomization unlocked, Female Henchmen and River Bridge). This is what I could find when I searched for the Strength ability, in the CoreAbilities.xml (which seems to be the relevant file):

<AbilityBonus InternalName="StrengthAbility">

        <AbilityBonusType>Unit_Design</AbilityBonusType>
        <AbilityBonusOption InternalName="Strength">
            <DisplayName>Strength</DisplayName>
            <Description>+20 Weight Capacity</Description>
            <Icon>Ability_Strength_Icon.png</Icon>
            <GameModifier>
                <ModType>Unit</ModType>
                <Attribute>AdjustUnitStat</Attribute>
                <StrVal>UnitStat_WeightCapacity</StrVal>
                <Value>20</Value>
            </GameModifier>
            <AdditionalTrainingTurns>8</AdditionalTrainingTurns>
            <HideWhenUpgraded>0</HideWhenUpgraded>
            <Type>Aggressive</Type>
            <AIData AIPersonality="AI_General">
                <AIPriority>5</AIPriority>
            </AIData>
        </AbilityBonusOption>
    </AbilityBonus>
    <AbilityBonus InternalName="StrengthAbility_Level">
        <AbilityBonusType>Unit_Level</AbilityBonusType>
        <AbilityBonusOption InternalName="Strength_Level">
            <DisplayName>Strength</DisplayName>
            <Description>+20 Weight Capacity</Description>
            <Icon>Ability_Strength_Icon.png</Icon>
            <GameModifier>
                <ModType>Unit</ModType>
                <Attribute>AdjustUnitStat</Attribute>
                <StrVal>UnitStat_WeightCapacity</StrVal>
                <Value>20</Value>
            </GameModifier>
            <HideWhenUpgraded>0</HideWhenUpgraded>
            <Likelihood>400</Likelihood>
            <RarityDisplay>Common</RarityDisplay>
            <Type>Aggressive</Type>
            <AIData AIPersonality="AI_General">
                <AIPriority>5</AIPriority>
            </AIData>
        </AbilityBonusOption>
    </AbilityBonus>

Of course, this is all gibberish to me. Can you see what's wrong, or point me in the right direction and tell me how to fix this?

EDIT: Also, do I need to start a new game for a fix in an xml-file to take effect? I think I remember reading that somewhere.

Thanks in advance.