Single Select Pick List value is not populating in Config through Rest API

Summary

Single Select Pick List value is not populating in Config through Rest API

Content

Hi,

We added the "region" field (SSPL) in Config and added it in payload and the payload is running successfully, but when we go to the transaction and check the region field through Reconfigure, this region SSPL is showing blank and it is not populating with the provided value in payload.

METHOD : POST

REQUEST URL : https://xxxx.bigmachines.com/rest/v8/config/actions/_bulkAddToTxn
SAMPLE REQUEST PAYLOAD:

{
"bsId": 39353919,
"documentId": 36244074,
"items": [
{
"productFamily": "vision",
"productLine": "servers",
"model": "serverSolutions",
"configData": {
"region": {"displayValue": "Central", "value": "Central"},
}
}
]
}

 

What are we missing here? What is the correct syntax to add for SSPL in payload?