I am creating an inventory tracker. I have a SharePoint list with the inventories that are in a gallery with a checkbox next to each item. The user selects which items they would like to update, hits update, and a collection (checkedItems) is made with all of the items that were checked. The user then puts in how many they would like to Add or Take, and that number is used to alter the SharePoint list's item quantity. Screenshots are below.
The issue I am having is that the formula in the LookUp function is just not working. I can't seem to find the right syntax to compare the datasource's item IDs to the collection's to find the right record to Patch. Here is my code for the Add button:
ForAll(checkedItems,Patch('Inventory Tracking - TESTING',LookUp('Inventory Tracking - TESTING',ID=checkedItems.ID),{Quantity:Quantity+TextInput2_3})) ; Set(_popup,false) ; Set(isChecked,false) ; Set(isChecked,true) ; Clear(checkedItems)
**Screen 1

**Collection of checked items

**Add button in context of app

Any thoughts are welcome!