Emails are not being received by participants part of an email group

We have designed a custom object and a web service in Application Composer. It works whenever there is a failure of the Change Order in the Integration Queue, a mail notification would be sent to the Change Analyst. We have also included a group mail in the workflow to send the notification to all members in the queue. However, the email notification is sent to individual users but not to a particular email group i.e. "xxxx_errored_COs@thermofisher.com"

Interestingly, the issue is just with this specific email group. It works well with the other email group.