This may be an isolated incident, but when I spawned into The Pyramidion strike, I spawned in the entrance to the Aphix Conduit Lost Sector. When I made my way to The Pyramidion's entrance, none of the ads spawned, and the plates did not progress. I think this may have something to do with the Contact PE, but now that I think about it, there's another possibility: the first fireteam member spawned into the strike, and while waiting for the two others to spawn in, went into the lost sector - maybe the ads didn't spawn because we weren't all in The Rupture. Regardless, it would be good to look into this if it becomes a recurring issue.