Hammer CLI

hammer role create --name a
hammer user-group create --name ug1 --admin true --roles 'a,m'
User group [ug1] created.

But after checking the logs that only role with id = 1 was added.

This is caused by how resolver is counting expected records.
It tries to guess if it is looking up records for resource in singular or plural from the options.
When both (e.g. --name and --names) are present it will pick singular and thus expects just one record.
In the example above the scoped options contain both name = ug1 and names = 'a,m' and the logic fails.