What happened?
eksctl scale nodegroup --config-file config.yaml --name <nodegroup> results in node group <nodegroup> not found

What you expected to happen?

1. eksctl scale nodegroup --config-file config.yaml --name <nodegroup> should succeed in applying the current desiredCapacity, minSize, maxSize properties of the nodeGroups/managedNodeGroups instance(s) from the config.yaml file.

2. Also would be great if --name could be omitted (not required) in which case ALL nodegroups would be scaled to current supplied config spec.

How to reproduce it?

1. Launch a cluster using a valid config.yaml with at least one nodegroup and then attempt: eksctl scale nodegroup --config-file config.yaml --name <nodegroup> where config.yaml is your cluster configuration file and <nodegroup> is the name of one of your node groups defined in that cluster config file.

Also note that eksctl scale nodegroup --cluster <cluster> --name <nodegroup> --minSize 0 works fine even when using the same values that should be read from config.yaml if --config-file config.yaml were to be used instead. In other words, the bug appears specific to the --config-file config.yaml option.

Anything else we need to know?
macOS Homebrew eksctl binary

Versions
Please paste in the output of these commands:

$ eksctl 0.27.0
$ kubectl 1.16.9