I am in the same boat. I have completed all the main missions in Stormriven and the Floating Island. I did the last mission in Stormriven "An Old Sea Chantry" and still no mission to enter the Science Center. I did not do all the side missions but I did not have to gain entrance to Stormriven. I wish KI would have a better way of directing us to main areas.
You have to do all the main missions in Stormriven, my problem was I did those missions but there was a glitch that did not show the last two missions. I emailed tech support and with in two days problem solved. Thank you KI!!!