This is an odd bug, have you been messing with the xml? Ongr can be found in the CoreUnits File. His part looks like this.

    <UnitType InternalName="Unit_Juggernaut_Ongr">
        <DisplayName>Ongr the Unbound</DisplayName>
        <CreatureType>Twisted</CreatureType>
        <RaceType>Race_Type_Trogs</RaceType>
        <Gender>Male</Gender>
        <IsSovereign>0</IsSovereign>
        <AllowGrouping>0</AllowGrouping>
        <SpawnRating>7</SpawnRating>
        <LevelMilestone InternalName="L1">
            <Level>1</Level>
            <UnitStat_ChanceToAvoidProne>100</UnitStat_ChanceToAvoidProne>
            <UnitStat_CombatSpeed>26</UnitStat_CombatSpeed>
            <UnitStat_HitPoints>50</UnitStat_HitPoints>
            <UnitStat_WeightCapacity>200</UnitStat_WeightCapacity>
        </LevelMilestone>
        <SelectedAbilityBonusOption>Juggernaut</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>IgnorePain</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>BrutalNature</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Maul</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Sweep</SelectedAbilityBonusOption>
        <Equipment>Greatsword_Void</Equipment>
        <Equipment>Juggernaut_Hair</Equipment>
        <Treasure>
            <Liklihood>100</Liklihood>
            <GameModifier>
                <ModType>GiveItem</ModType>
                <Attribute>Greatsword_Void</Attribute>
            </GameModifier>
        </Treasure>
        <Backstory>"Feel no pain. Know no fear. Need no rest. Fight till the foe falls. Then seek the next battle." These are the watchwords of the yatra nata - the Juggernauts - the elite among all Trog warriors, soldiers segregated from their brethren on their eleventh name day for special training. History says their first battle came a dozen years after the Quendar conquered Teroth-Nu, when eight of them overthrew a city full of Magnar II’s troops, and retook Kir-Tion’s throne.</Backstory>
        <AnimationPack>JuggernautAnimationPack</AnimationPack>
        <BattleAnimationBehavior>Stationary</BattleAnimationBehavior>
        <ClothMapScale>1.6</ClothMapScale>
        <ClothPoseIndex>1</ClothPoseIndex>
        <Color_Clothing1>20,20,20,255</Color_Clothing1>
        <Color_Clothing2>20,20,20,255</Color_Clothing2>
        <Color_Hair>20,20,20,255</Color_Hair>
        <Color_Metal>20,20,20,255</Color_Metal>
        <Color_Skin>20,20,20,255</Color_Skin>
        <CutSceneDataPack>JuggernautUnitCutscenePack</CutSceneDataPack>
        <EquipmentScale>2.5</EquipmentScale>
        <EyeTexture>gfx/eyes/male_brown_eye.png</EyeTexture>
        <InfoCardBackground>BG_EmpireRugged</InfoCardBackground>
        <ModelPath>K_Juggernaut_Mesh_01.hkb</ModelPath>
        <ModelScale>0.8</ModelScale>
        <MovingSFX>TEMP_KnightMarching1</MovingSFX>
        <OnHitParticleName>Bloody_OnHit</OnHitParticleName>
        <SkeletonPath>K_Juggernaut_Skeleton_01.hkb</SkeletonPath>
        <SoundPack>SoundPack_Juggernaut</SoundPack>
        <TacticalModelScale>1.5</TacticalModelScale>
        <Texture_Skin>M_Juggernaut_Texture_02.dds</Texture_Skin>
        <UnitModelType>JuggernautMale</UnitModelType>
    </UnitType>

He shouldn't be buildible for various reasons but you could try inserting something like the below code into the above and saving it as a xml file in the mods folder, which can be found in Documents\My Games\LegendaryHeroes\Mods.

        <Prereq>
            <Type>AbilityBonusOption</Type>
            <Attribute>None</Attribute>
            <Target>Player</Target>
        </Prereq>

full deletion and reinstall seems to have done the trick