Azure AI Studio Chat Ground issue with configuring Azure AI Search Index Data Source

I've set up an Azure AI search index data source in Azure AI Studio Chat Ground using the "Add your data" option. The Azure AI search index contains valid documents sourced from Blob storage and the search functionality is working fine. However, when initiating a conversation in the chat window, I encounter the following error message:

Validation error at #/data_sources/0/AzureCognitiveSearch/parameters/fieldsMapping/contentFields/0: Input should be a valid string  

Search index first field is of string format

I tried with and without using custom field mapping on different indexes but getting same error. Any insights or guidance on what might be causing this error and how to resolve it would be greatly appreciated. Thank you.