SQL Server Update trigger not working correctly - sql-server

Question

I have written an UPDATE trigger to look for changes in my Test.dbo.receiving_podio_dump table and then perform one of two different scenarios:
IF there is an existing receiving_id and existing sku_no match and this is an update to that combination in the Test.dbo.receiving_detail table, the appropriate row gets updated, OR
IF there is an existing receiving_id and but a new sku_no item, a new row needs to be added/inserted into the Test.dbo.receiving_detail table.
Here is my trigger:
CREATE TRIGGER trigger_receiving_detail_sku1_update
ON [Test].[dbo].[receiving_podio_dump]
FOR UPDATE
AS
BEGIN
--UPDATES DATA IN THE ROW FOR THAT RECEIVING LOG/SKU NO COMBO IF IT ALREADY EXISTS--
IF (SELECT ISNULL(COUNT(*), 0)
FROM inserted
LEFT JOIN dbo.receiving_detail AS rec ON (inserted.receiving_id = rec.receiving_id AND '001' = rec.sku_no)) <> 0
BEGIN
UPDATE [dbo].[receiving_detail]
SET receiving_assigned_id = inserted.receiving_assigned_id,
sku_id = sku1_id, sku = sku1, sku_lot = sku1_lot,
sku_whloc = sku1_whloc, sku_weight_of_unit = sku1_weight_of_unit,
sku_unit_of_weight_type = sku1_unit_of_weight_type,
sku_quantity_of_units = sku1_quantity_of_units,
sku_unit_of_measure = sku1_unit_of_measure,
sku_temperature = sku1_temperature
FROM inserted
WHERE ([dbo].[receiving_detail].receiving_id = inserted.receiving_id
AND [dbo].[receiving_detail].sku_no = '001')
END
--INSERTS A ROW FOR A NEW SKU NO FOR AN EXISTING RECEIVING LOG NUMBER--
IF (SELECT ISNULL(COUNT(*), 0)
FROM inserted
LEFT JOIN dbo.receiving_detail AS rec ON (inserted.receiving_id = rec.receiving_id AND '001' = rec.sku_no)) = 0
BEGIN
INSERT INTO [dbo].[receiving_detail] (receiving_id, receiving_assigned_id, sku_id, sku_no, sku, sku_lot, sku_whloc, sku_weight_of_unit, sku_unit_of_weight_type, sku_quantity_of_units, sku_unit_of_measure, sku_temperature)
SELECT
inserted.receiving_id, inserted.receiving_assigned_id, sku1_id,
'001', sku1, sku1_lot, sku1_whloc, sku1_weight_of_unit,
sku1_unit_of_weight_type, sku1_quantity_of_units,
sku1_unit_of_measure, sku1_temperature
FROM
inserted
WHERE
sku1 IS NOT NULL
END
END
GO
The first part of the trigger is working, and quantities of products are being updated on the Test.dbo.receiving_detail table if there is an update in the Test.dbo.receiving_podio_dump table.
However, if a totally new SKU is being added, a new row is not being inserted into my Test.dbo.receiving_detail table.
I am at a loss as to what to change, I have tried several things, any advice is welcome and appreciated. Thanks!
PS: the receiving log has a total of 24 SKU Items that can potentially be added or updated. I have only included the first trigger, but all of them follow this pattern.

Answer 1

I remove both IF statements and added those Conditions on the UPDATE and INSERT statements to support the scenario of a mass update with both conditions are true.
CREATE TRIGGER trigger_receiving_detail_sku1_update
ON [Test].[dbo].[receiving_podio_dump]
FOR UPDATE
AS
BEGIN
--UPDATES DATA IN THE ROW FOR THAT RECEIVING LOG/SKU NO COMBO IF IT ALREADY EXISTS--
UPDATE rec
SET receiving_assigned_id = i.receiving_assigned_id,
sku_id = sku1_id, sku = sku1, sku_lot = sku1_lot,
sku_whloc = sku1_whloc, sku_weight_of_unit = sku1_weight_of_unit,
sku_unit_of_weight_type = sku1_unit_of_weight_type,
sku_quantity_of_units = sku1_quantity_of_units,
sku_unit_of_measure = sku1_unit_of_measure,
sku_temperature = sku1_temperature
FROM inserted i
INNER JOIN [dbo].[receiving_detail] rec ON rec.receiving_id = i.receiving_id
WHERE (rec.sku_no = '001')
--INSERTS A ROW FOR A NEW SKU NO FOR AN EXISTING RECEIVING LOG NUMBER--
INSERT INTO [dbo].[receiving_detail] (receiving_id, receiving_assigned_id, sku_id, sku_no, sku, sku_lot, sku_whloc, sku_weight_of_unit, sku_unit_of_weight_type, sku_quantity_of_units, sku_unit_of_measure, sku_temperature)
SELECT
i.receiving_id, i.receiving_assigned_id, sku1_id,
'001', sku1, sku1_lot, sku1_whloc, sku1_weight_of_unit,
sku1_unit_of_weight_type, sku1_quantity_of_units,
sku1_unit_of_measure, sku1_temperature
FROM
inserted i
WHERE sku1 IS NOT NULL
AND NOT EXISTS (SELECT * FROM [dbo].[receiving_detail] rec WHERE rec.receiving_id = i.receiving_id AND rec.sku_no = '001')
END
GO