ForeignKeyOf Not displaying in DAC Browser

Hello everyone,

I am developing a custom screen and ran into an issue. I have set up PrimaryKeyOf on the parent DAC, and ForeignKeyOf + PXParent + PXDBDefault on the child DAC, but this does not show up on the DAC schema browser. I noticed this because my PXFormula(...SumCalc<>) was not working.

Parent DAC:

[Serializable]
[PXCacheName("NPDHeader")]
[PXPrimaryGraph(typeof(NPDApprovalEntry))]
public class NPDHeader : PXBqlTable, IBqlTable
{
    #region Keys
    public class PK : PrimaryKeyOf<NPDHeader>.By<projectNo, productTitle>
    {
        public static NPDHeader Find(PXGraph graph, string projectNo, string productTitle, PKFindOptions options = PKFindOptions.None) => FindBy(graph, projectNo, productTitle, options);
    }
    public static class FK
    {

    }
    #endregion

    #region ProjectNo
    [PXDBString(15, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Project No", Enabled = false)]
    [AutoNumber(typeof(ISOSetup.autoNumberingNPDApproval),
        typeof(NPDHeader.date))]
    [PXSelector(typeof(NPDHeader.projectNo),
        typeof(NPDHeader.productTitle), ValidateValue = false)]
    public virtual string ProjectNo { get; set; }
    public abstract class projectNo : PX.Data.BQL.BqlString.Field<projectNo> { }
    #endregion

    #region ProductTitle
    [PXDBString(128, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Product Title")]
    [PXDefault]
    public virtual string ProductTitle { get; set; }
    public abstract class productTitle : PX.Data.BQL.BqlString.Field<productTitle> { }
    #endregion




//Other Fields




     #region TotalCost
 public abstract class totalCost : BqlDecimal.Field<totalCost> { }

 [PXDBDecimal(6)]
 [PXFormula(null, 
     typeof(SumCalc<NPDDesignMatlCost.totalCost>))]
 [PXDefault(TypeCode.Decimal, "0.00", PersistingCheck = PXPersistingCheck.Nothing)]
 [PXUIField(DisplayName = "Total Cost", Enabled = false)]
 public virtual decimal? TotalCost
 {
     get;
     set;
 }
 #endregion
}

Child DAC:

[Serializable]
[PXCacheName("NPDDesignMatlCost")]
public class NPDDesignMatlCost : PXBqlTable, IBqlTable
{
    #region Keys
    public class PK : PrimaryKeyOf<NPDDesignMatlCost>.By<projectNo, productTitle, matlLineNbr>
    {
        public static NPDDesignMatlCost Find(PXGraph graph, string projectNo, string productTitle, int matlLineNbr, PKFindOptions options = PKFindOptions.None) => FindBy(graph, projectNo, productTitle, matlLineNbr, options);
    }
    public static class FK
    {
        public class Approval : NPDHeader.PK.ForeignKeyOf<NPDDesignMatlCost>.By<projectNo, productTitle> { }
    }
    #endregion

    #region ProjectNo
    [PXDBString(15, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Project No")]
    [PXParent(typeof(FK.Approval))]
    [PXDBDefault(typeof(NPDHeader.projectNo))]
    public virtual string ProjectNo { get; set; }
    public abstract class projectNo : PX.Data.BQL.BqlString.Field<projectNo> { }
    #endregion

    #region ProductTitle
    [PXDBString(128, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Product Title")]
    [PXDBDefault(typeof(NPDHeader.productTitle))]
    public virtual string ProductTitle { get; set; }
    public abstract class productTitle : PX.Data.BQL.BqlString.Field<productTitle> { }
    #endregion

    //Other Fields

}

DAC Schema Browser:

DAC Schema Browser Child DAC:

[Serializable]
[PXCacheName("NPDDependency")]
public class NPDDependency : PXBqlTable, IBqlTable
{
    #region Keys
    public class PK : PrimaryKeyOf<NPDDependency>.By<projectNo, productTitle, dependencyID>
    {
        public static NPDDependency Find(PXGraph graph, string projectNo, string productTitle, int dependencyID, PKFindOptions options = PKFindOptions.None) => FindBy(graph, projectNo, productTitle, dependencyID, options);
    }
    public static class FK
    {
        public class Approval : NPDHeader.PK.ForeignKeyOf<NPDDependency>.By<projectNo, productTitle> { }
    }
    #endregion

    #region ProjectNo
    [PXDBString(15, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Project No")]
    [PXParent(typeof(FK.Approval))]
    [PXDBDefault(typeof(NPDHeader.projectNo))]
    public virtual string ProjectNo { get; set; }
    public abstract class projectNo : PX.Data.BQL.BqlString.Field<projectNo> { }
    #endregion

    #region ProductTitle
    [PXDBString(128, IsKey = true, IsUnicode = true, InputMask = "")]
    [PXUIField(DisplayName = "Product Title")]
    [PXDBDefault(typeof(NPDHeader.productTitle))]
    public virtual string ProductTitle { get; set; }
    public abstract class productTitle : PX.Data.BQL.BqlString.Field<productTitle> { }
    #endregion

    //Other Fields

}

Does anyone have any idea as to how/why this is happening?