Just wanted to pass this on since I did not see a thread about it; I already submitted a ticket and got a response.
Basically, I successfully completed my first raid (Siege the Stronghold) with my guild this past Saturday, but the Raid Mastery line did not unlock for me. I earned the “Mine Control”, “Scourge of the White Mantle”, and “Siege the Stronghold” achievements along with 1 mastery point. I was also able to get my rewards from the chest, which included a Legendary Insight and the “tome” to unlock the Legendary Armor collection I.
Unfortunately, the response I got from ANET states they cannot unlock the mastery line for me, but has passed the issue on the appropriate team.
After many attempts to finish a raid, this is a let down.