Thanks for your inquiry. I have tested the scenario with a Word file from Aspose default storage and unable to notice the reported issue. Please note V4 API Version supports JSON Web Token authentication only. Please try the following cURL example, hopefully it will resolve the issue. However, if the issue persists, then please share your sample input document here. We will further investigate the issue and guide you accordingly.
// First get JSON Web Token
// Get App Key and App SID from https://dashboard.aspose.cloud/
curl -v "https://api.aspose.cloud/connect/token" -X POST -d "grant_type=client_credentials&client_id=[MyAPP_SID]&client_secret=[MyAPP_KEY]" -H "Content-Type: application/x-www-form-urlencoded" -H "Accept: application/json"
// Split Word Document and Save to ZIP file
curl -X PUT "https://api.aspose.cloud/v4.0/words/TOC_Test.docx/split?format=png&zipOutput=true" -H "accept: application/json" -H "authorization: Bearer [Access_Token]"
As suggested above, you need to use JSON Web Token authentication with V4 API Version instead of Oauth2. Please check again sample authentication cURL code, it will help you to accomplish the task.
// First get JSON Web Token
// Get App Key and App SID from https://dashboard.aspose.cloud/
curl -v "https://api.aspose.cloud/connect/token"
-X POST
-d "grant_type=client_credentials&client_id=[MyAPP_SID]&client_secret=[MyAPP_KEY]"
-H "Content-Type: application/x-www-form-urlencoded"
-H "Accept: application/json"