AWS Beanstalk deployment failing - missing bucket_name

Within the last few days Travis deployments to AWS Beanstalk have been failing with a persistent missing bucket_name error. The bucket_name property is provided in the .travis.yml file and is correct in regards to the AWS details.
I have noticed that in the “View Config” link next the builds logs, the actual build file that is generated from the script and sent to AWS is wrong.
It is actually showing a bucket property, instead of a bucket_name property. I have checked previous builds and the file shows the correct bucket_name property.
Has something changed in regards to this setup? Or is this a regression?

Thank you!