I have set up a new user in CRM who has the same permissions and belongs to the same groups as other team members. When just this user is assigned to a deal this user isn't triggering email notifications sent by a workflow rule  when a deal reaches a set stage. All the other users in the same group trigger the email notifications when deals get to the set stage, these emails show as being sent by the workflow rule in the timeline of the deal and they receive the emails.

Any ideas?

It's as if the new user isn't in the group - but they are!