I have setup 3 tables.

1. Product data

2. Universal Part Numbers

3. Parts

Every Part has a parent product. Some parts have a universal part number.

I then import the parts data, I am linking one filed that contains the Product ref (SKU) and another that contains the universal part number (UPN), where there is one.

https://ibb.co/7WWbCYt

https://ibb.co/xhM7zZH

The import works correctly for the universal part numbers, with each UPN record being linked to the correct record in the Parts table. The link to the Product table is not formed however, and I can't work out why. Does anybody have any suggestions as to what could be going wrong?

Thanks!