I have had this same problem. Unmask "Those Accross the Sea" failed to trigger after I completed Investigate Strange Chalk Markings. I did not get the wartable mission you are supposed to get for the chantry garden and I didn't get the mission where you reconcile Celene and Michel de Chevin even though I am certain I met the conditions for all of these things.
This must be some kind of bug. I seriously hope they fix it.
