Can't run 'rails console' on Elastic Beanstalk Amazon Linux 2

I'm working on upgrading a Rails 6 EB environment to Amazon Linux 2.

The app is working fine, but I'm having trouble running rails console on the environment.

Normally, I'd do something like this:

• eb ssh
• cd /var/app/current
• sudo su
• bundle exec rails c

But now, on Amazon Linux 2, it throws an error that my gems aren't installed. They seem to be installed in the vendor directory as part of the deployment, but bundler isn't recognising these.

To work around this, I have to manually run bundle install - which adds a couple of minutes whenever I have to run a console command.

Is there a solution to get this working again as easily as it did on Amazon Linux 1?