For my Sharepoint list, I have this column that feeds its information from a Combobox. The Items property is a big Excel table that can have many coincidences, where the only thing that changes is ListPrice and Country. Like this:

The Combobox should display ListPrice. But the table should be filtered from ArtNumber and Country. The problem I have is that I have maaaaaaaaaaaany Sharepoint columns/comboboxes like this. So if variables or anything too complex like that can be avoided, would be awesome. Meaning, I would like that each individual combobox did its own thing.
I thought I could acheive the filtering I need with two codes: editing Items and DefaultSelectedItems property of each comboBox:
ITEMS: Filter(EXCELtable; ArtNumber = Label1.Text)
DEFAULTSELECTEDITEMS: LookUp(EXCELtable; Country = DataCardValue5.Selected.Value)
Label1.Text is how the user inputs each ArtNumber. And DataCardValue5 is how user inputs the country.
This was working how I wanted it to, but then randomly it stopped working. After, I tried swapping the ArtNumber and Country between the Items and DefaultSelectedItems to see if it will fix it, but no.
Any ideas? Maybe a formula for DefaultSelectedItems that boths filters the ExcelTable and LookUps specifically? This way I'll get the ArtNumber and country specific item.