Hello, 

Facing same issue in both our Workspaces, our Cluster logs suddenly stopped being delivered to S3 on 12th of March. There were no changes on Cluster settings nor IAM side, also all IAM Permissions should be in place according to Databricks Official Documentation. 

For testing, SSH-ing into one of the Databricks Workers in AWS and uploading a file to S3 was working fine.

Any hints would be highly appreciated.