InternalServerError with SageMaker Batch transform job

We have a few thousand models on SageMaker backed by our own containers on ECR. We have a problem with one of the models that when we start a Batch transform job with it the job is pending, then after ~20 minutes the job is marked as failed with "InternalServerError: We encountered an internal error. Please try again.". Attempting the job again didn't help. Is there any way to debug this?

The models execution role, container, security group and subnets are set correctly. The containers are all in the same repo which the execution role has permission to access. The container image is ~3GB, but is definitely not the largest one that we have run, and all our other models run fine with the same job parameters.