For troubleshooting any issues with AWS DMS, it is necessary to have logs enabled. The DMS logs would typically give a better picture and helps find errors or warnings that would indicate the root cause of the failure. If the logs are not available there is nothing much you can do from a detailed troubleshooting analysis perspective. So basically next step is to turn on DMS logs and kick the job again and validate if the errors are captured in the logs.
If logs are not enabled, you need to set up a new task with logging enabled so if and when it errors out, you can take a look and troubleshoot the same.
I’ll save my full rant for another day, but I’m not that impressed with DMS. It could be a failing on my part, though.