The Therassic Spire (Kaer Maga) Mystery

I remember in (I think) ‘City of Strangers’ that the Therassic Spire mysteriously closed and barred its doors.

Has there been anything published that expounds on that or resolves it?

Are there any published NPCs tied to the Therassic Spire?

I believe that was the shattered star AP that covered that plot in one of the books.