I can't replicate that in 2023 for type or instance parameter:
Incidentally if you use SetValueString it will convert the double input to a string but then likely get it wrong because this method expects display units not internal units. It will only get it right if the display units and the internal units are the same. However, this method shouldn't be used in most cases since it has more overhead. I think you may know this but since you've provided no code I can only guess what you know.
Private Function Obj_220925a(ByVal commandData As Autodesk.Revit.UI.ExternalCommandData,
ByRef message As String, ByVal elements As Autodesk.Revit.DB.ElementSet) As Result
Dim UIDoc As UIDocument = commandData.Application.ActiveUIDocument
If UIDoc Is Nothing Then Return Result.Cancelled Else
Dim IntDoc As Document = UIDoc.Document
Dim Kg As Double = 100
Dim m2 As Double = 10
Dim KgPerSqFt = Kg / (m2 * (1000 / 304.8) ^ 2) 'Internal
Dim KgPerSqm = Kg / m2
Dim V0 = UnitUtils.ConvertToInternalUnits(KgPerSqm, UnitTypeId.KilogramsPerSquareMeter)
Dim V1 = UnitUtils.ConvertFromInternalUnits(V0, UnitTypeId.KilogramsPerSquareMeter)
Debug.WriteLine(KgPerSqm)
Debug.WriteLine(V0)
Debug.WriteLine(V1)
Debug.WriteLine(KgPerSqFt)
Dim R As Reference = Nothing
Try
R = UIDoc.Selection.PickObject(Selection.ObjectType.Element)
Catch ex As Exception
Return Result.Cancelled
End Try
Dim El As Element = IntDoc.GetElement(R)
Using Tx As New Transaction(IntDoc, "Change Param")
If Tx.Start = TransactionStatus.Started Then
Dim Px As Parameter = El.LookupParameter("RPT_MassPerArea")
Dim Py As Parameter = IntDoc.GetElement(El.GetTypeId).LookupParameter("RPT_MassPerAreaOnType")
If Px Is Nothing OrElse Py Is Nothing Then
Tx.RollBack()
Else
Px.Set(V0)
Py.Set(V0 * 2)
'I just multiplied it by 2 to distinguish it in the type
'Py.SetValueString(V0) 'This may cause you issues since display units are expected.
Tx.Commit()
End If
End If
End Using
Return Result.Succeeded
End Function
