UDF not updating value when Excel opened through code

I've been trying the solutions I've found for similar questions, but it doesn't seem to be working to resolve my problem.

I have an Access database (Access 2016), which opens an Excel spreadsheet (Excel 2016) which does calculations. I also have an Excel Add-In file that contains a ton of UDFs. By default, I always have this Add-In installed in Excel and it's part of my profile boot script. However, when Access opens Excel through code, it doesn't recognize the Add-In (whereas opening Excel myself does work). So I've added code (per other forum suggestions) to uninstall and reinstall the Add-In after Excel opens. See code below.

    Dim appExcel As Object
    Dim strpath As String

    strpath = "H:\Folder\Calculator.xlsm"

    Set appExcel = CreateObject("Excel.Application")
        appExcel.Workbooks.Open FileName:=strpath, UpdateLinks:=1, ReadOnly:=True

    Set wbk = appExcel.ActiveWorkbook
        appExcel.AddIns.Add FileName:="H:\Folder\AddInFile.xlam"

    If appExcel.AddIns("AddInFile").Installed = False Then
        appExcel.AddIns("AddInFile").Installed = True
    Else
        appExcel.AddIns("AddInFile").Installed = False
        appExcel.AddIns("AddInFile").Installed = True
    End If

    Set appExcel = Nothing

The only way to get my UDFs to work correctly requires me to go into every cell that contains one of these functions and manually force it to recalculate (F2-Enter). Forcing a recalculation on the entire worksheet doesn't help. It must be cell by cell. The formulas "execute" but have incorrect results until I force them to recalculate. Below is an example of one such function.

    Function Nx(Age, table, Interest)

    Dim l(0 To 121) As Double
    Dim D1(0 To 121) As Double
    Dim N1(0 To 121) As Double
    Dim v As Double
    Dim NAge As Double

    If Age > 120 Then
            NAge = 120
    Else
        NAge = Age
    End If

    l(0) = 9999.9999
    v = 1 / (1 + Interest)
    D1(0) = l(0)
    Nn = D1(0)
    x1 = Int(NAge)
    x2 = Int(NAge) + 1
    Fract = NAge - x1

    For j = 1 To 120
        l(j) = l(j - 1) * (1 - q(table, j - 1))
        D1(j) = l(j) * (v ^ j)
        Nn = Nn + D1(j)
    Next j

    N1(0) = Nn

    For j = 1 To 120
        N1(j) = N1(j - 1) - D1(j - 1)
    Next j

    Na = N1(x1) - D1(x1) * (11 / 24)
    Nb = N1(x2) - D1(x2) * (11 / 24)
    Nx = ((1 - Fract) * Na) + (Fract * Nb)

    End Function 

This function works perfectly under any other circumstance. However, when you open Excel programmatically, it stops returning correct results. If you save the file and reopen it, everything updates correctly.

I can't seem to figure out a solution. I previously asked this question, but the first response requested a sample of code and down-voted my question, and after a few weeks no one had tried answering me. I really need to figure out a solution to this, so I figured I would try again with a fresh question.