AWS Code Pipeline Failed replicating artifact

Question

I have a build pipeline that has a source of AWS Code Commit. When there is a commit, this runs a build script in AWS Code Build that builds the project, builds a docker image and pushes into ECR. The final stage deploys the docker image into an ECS cluster in a different region which fails with the following error:

Replication of artifact 'BuildArtifact' failed: Failed replicating artifact from bucket 1 in region 1 to bucket 2 in region 2: Check source and destination artifact buckets exist and pipeline role has permission to access it.

Bucket 1 does have the artifact in it, but bucket 2 is empty. I have tried giving the code pipeline role full access to S3, but didn't change anything. There is nothing in cloud trail regarding the error. This question discuses a similar issue but I believe this is no longer relevant as the way cross region deployments work has changed since then. I have tried re-creating the pipeline (with the same parameters) but this still gives the same error. Perhaps there is some additional permission it needs that AWS didn't create.

If anybody could tell me how to fix, or debug this issue, it would be appreciated.

Thanks, Adam