1. Check whether the Agent’s Profile have Read and Create access to the Contact object.

2. Check whether the Automated Process also have Read and Create access to the Contact object.

3. Check whether any fields are made mandatory recently at field level. If yes, remove it on the field level and make it required on the page layout level.

4. Check whether any new Validation Rules are added to the Contact object. If yes, bypass it.

5. Check whether Duplicate Rules are preventing it. If yes, check the Duplicate Rules.

6. If the issue is consistent, setup Debug Logs for Automated Process user.