Workmail misses to redirect to main receiver

A mail coming from external big party/company to my company 3 receivers , A as main and B and C as CC. A, B and C är "groups" and mail is redirecting to an account in Workmail managing the final redirect to other external accounts for A, B and C according to set rules. A does not receive anything but B and C do. Another mail later sends redirection to A. In other cases the redirection for A, B and C works as for a number of other "groups" in our solution. What is this? A glitch? A missconfiguration? Does A have some special status?