It’s a known issue and strictly UI related. Dev Tracker helps.
https://forums.elderscrollsonline.com/en/discussion/comment/5712153#Comment_5712153
I saw that you can get tickets by taking a keep, assuming this is right? Well the group I was with took one (after a wonderful 13fps battle) and no event tickets. So either I was misinformed and you don't get tickets that way, or there is an issue. Either way, I don't need the event tickets THAT bad. Spending more than 10 minutes in Cyro would drive me insane