Stack Create Fails: Internal Failure. Rollback requested by user.

I am creating a stack via the AWS Ruby SDK v3 and it is failing with an internal error. After a long period (30-40 minutes) it fails and rolls back with an internal failure. No resources show up and there are no other events.

24 May 2019 07:32:08 stack-name ROLLBACK_COMPLETE -
24 May 2019 07:31:42 stack-name ROLLBACK_IN_PROGRESS Internal Failure. Rollback requested by user.
24 May 2019 07:05:10 stack-name CREATE_IN_PROGRESS User Initiated

Launching the stack as a different (more privileged) user means that it starts immediately. I have also tried removing all resources from the stack except for one EC2 instance and the same behaviour is exhibited.

The stack is launched with capabilities CAPABILITY_IAM and CAPABILITY_NAMED_IAM .
My best guess is that the user is missing an IAM policy which allows it to even start processing the stack, but I don't know how to debug it. It's a role that is used by many other deployments and cannot be easily changed.
Any guidance on how to debug or what might cause this behaviour is appreciated.