Hi guys, the ams builder problem has drifted into a network problem with the S3 bucket used as registry backend. The difference with pushing layers from other regions is that the bucket has S3 Transfer Acceleration enabled, so Amsterdam will go into AWS from a different entrypoint than others.
In the meantime we ~have destroyed~ are destroying all ams builders and instructed our system to recreate them in iad on your next application deploy.
cheers.