I had pre ordered and have access to the starter pack but just can’t access the Christmas themed mission. Really looking forward to it but I have difficulties in accessing it.
That’s strange. Supposedly you should be able to play it even if you don’t own the H1 locations Legacy pack, since you claimed to be an owner of at least the base game. I’d suggest you to send out a ticket to the official support page. There should be someone that can help you with this issue.
Visit the following website, then click the top right button to submit:
https://ioisupport.zendesk.com/hc/en-us