Ref column looking at wrong column - stumped!

[Chris_Bean1]

Hi folks

Strange one here - I've got a column set up as a ref to another tab, nothing weird there, but in the app UX it looks at a completely different column

When I go to the UX, it shows this - clearly not a list of store numbers! 

I've happily used refs before and the ref is working fine on the same data in another app. 

Help! 

Thanks

Chris