The following resource(s) failed to create: [SnsTopic]

We have a simple ApplicationJob with an s3_event trigger as follows:

class MySimpleJob < ApplicationJob

  s3_event 'my_bucket'
  def my_simple_handler
    # ...
  end
end

When I deploy with the s3_event line included, the stack fails with:

05:03:48PM CREATE_FAILED AWS::CloudFormation::Stack ExampleMySimpleJobStaging Embedded stack arn:aws:cloudformation:us-east-2:***:stack/example-MySimpleJobStaging-1EYT8QOFVW78C/8a92b800-e58e-11eb-8f46-020b81543b8a was not successfully created: The following resource(s) failed to create: [SnsTopic]. 

No further details are provided anywhere in the logs or in CloudFormation, and strangely, I can’t find that stack object anywhere when I poke around in CloudFormation. It only exists in the jets deploy output.

Is there some permission I need to enable on the S3 bucket or something?

By the way, we are in a VPC (and everything else is set up and working correctly – stack just fails when I include this job).

I have followed the instructions at https://rubyonjets.com/docs/events/s3/ but don’t see anything mentioning this error or any permissions that need to be set up to use s3_event.