Why is the target field showing multiple values if I have more than one line item?

You have simply mapped one field that repeats in a source structure. You need to add a loop to fix this issue following the below steps:

1. Right-click on mapping line
2. Click Target Variable > Add Position Variable
3. Click field father of the target field
4. Repeat step 1 and click Add Source Condition
5. Place the condition on the respect father field on source structure
6. Click Position Variable > OK

Please refer to launchpad KBA with detailed screenshots: Target Field concatenating instead of creating multiple lines in Managed Gateway for Spend&Network Mapping Tool - SAP Integration Suite, managed gateway for spend management and SAP Business Network.

We have also delivered a webcast where this topic was covered, you could find the recording in the SAP Article How to access Managed Gateway for Spend&Network Mapping Tool webcast recording.

Also, there is another way to perform the loop in Managed Gateway for Spend&Network Mapping Tool with the item Value Variable, you could find the steps to perform it in the SAP Article How can I perform the loop function in Managed Gateway for Spend&Network with value variable?

When using the loop functionality in Managed Gateway for Spend&Network Mapping Tool, it is a good practice to always set it after all source and target conditions. It is more certain that this will work if this is followed since the Managed Gateway for Spend&Network Mapping Tool perform the mappings in the order that it is maintained. So if the loop has a condition to happen, the loop won't follow the same if the loop is set before.

SAP Integration Suite Managed Gateway > Managed Gateway for Business Network SCC > Managed Gateway for Buyer Business Network SCC