Omnisend Email Marketing & SMS

I am a paid subscriber and just realised that discount codes are not being send to some customers in Welcome email :( I wrote to the support but gave me a very long procedure to resolve. Omnisend needs to work on this to ensure ALL the customers get automated discount codes.
REVIEW UPDATE; This was not Omnisend's fault. Omnisend then got back to me and explained me the situation. The customer was subscribed before I joined Omnisend hence I faced this issue. So thanks to support team for giving proper explanation.