If you're getting a successful response but the server isn't taking the expected action, please open a case with Genesys Cloud Care to investigate. We do not have access to your org's data via the forum to conduct such an investigation.
Data files that validate successfully take up to 24 hours to import. The import process, when in Pending status, completes at approximately 3:00 a.m. local time in each region.
Have you waited 24h?
From the same resource article it also notes that imported historical data is only for the automatic best method in forecasting:
Use the historical data import feature to upload historical interaction data. Workforce management uses this data to generate forecasts using the Automatic Best Method option.
After waiting 24h are you attempting to utilize the data via Automatic Best Method option?
If nothing obvious, then I would recommend opening a case with Care.
Hello, thank you for your feedback. I was finally able to do it. You have to use the Validate API and then the import goes on hold after that you have to wait 24h for the import to be validated.