This is a fairly commonly asked question, and the answer is not cut and dry or obvious. When calls are transferred from a user to a group or if the call is transferred to a group from an auto attendant the call recording functionality is set at the account level. This means if you have call recording configured for users only, features like groups, conference bridges, and even auto attendance will not have the benefit of call recording enabled.
As of right now, the only way to configure call recording for groups is to set call recording globally on your account. Below is a simple video to explain how to enable call recording on your account globally.